Greece's economic woes have drawn the eyes of a jittery world lately, with many observers fearing that the nation's debt crisis could throw the world economy back into a serious tailspin.

Things are so bad in Greece that some in their country were suggesting that the nation withdraw from the European Union and stop using the euro as the nation's currency. After Sunday's election results, that seems far less likely -- but that doesn't mean that Greece's problems are solved.

Still, as bad as things are for Greece, they're not alone in their struggles. Just look at the United States.

As is the case in Greece, the U.S. federal government's debt burden ($15.5 trillion) is larger than the country's entire economy, measured in terms of gross domestic product (GDP). The GDP is simply the total market value of all goods and services a country produces in a year.

The nation's debt to GDP ratio now exceeds 100%. So what does that mean? It means that all of the goods and services produced in the United States in one year still wouldn't be enough to pay off our nation's debt. And that's not healthy.

A Harvard study released in April found that countries with public debt levels exceeding 90% of GDP have historically experienced weakened economic growth. In the study (which included data dating back to the year 1800), researchers found that countries with a high debt-to-GDP ratio experienced an average economic growth rate of just 2.3%, versus the healthy 3.5% annual economic growth those same countries enjoyed in lower debt periods.

A heavy debt burden certainly threatens the prosperity of the United States. But while the U.S. federal government certainly has a debt problem on its hands, others, including Greece, have it far worse.

With data from the International Monetary Fund (IMF), here are the top 10 industrialized world countries that are drowning in federal debt based on their gross national debt to GDP ratios:

Note: U.S. dollar conversions on government debt and GDP are based on the Central Intelligence Agency's estimated foreign-currency-to-dollar rate for each country in the year 2011.

10. France -- Debt equals 86.3% of GDP


GDP: 1,995.34 billion Euros ($2.81 trillion)

Government Debt (Gross): 1,721.23 billion Euros ($2.42 trillion)

Even if the country is home to the lovely city of Paris, France's debt situation is far from romantic.

A damaging combination of high unemployment (9.1% in 2011), lower than expected economic growth, depressed tax revenues and continuously heavy social spending has led to sharp increases in France's public debt.

According to the Central Intelligence Agency's (CIA) World Factbook, these factors have caused France's gross-national-debt-to-GDP ratio to skyrocket from 68% in 2008 to 86% in 2011. As economic headwinds persist, don't expect France's debt problems to go away anytime soon.



9. Belgium -- Debt equals 98.5% of GDP


GDP: 368.98 billion Euros ($519 billion)

Government Debt (Gross): 363.46 billion Euros ($511 billion)

The 2008 financial crisis wasn't cheap for Belgium. Like in the United States, Belgium's government was forced to provide its own expensive financial bailout, injecting capital into three of the country's major troubled banks.

Things have been looking up in the country over the past year, however. Unemployment fell from 8.3% to 7.7% in 2011. Also, GDP grew 2.0%, and the federal deficit decreased from 6% in 2009 to 4.2% of GDP in 2011.

Nonetheless, with a debt-to-GDP ratio nearing 100%, many investors believe Belgium may be vulnerable in the short term to growing debt problems in the European Union. Belgium also faces two other major problems -- an increasingly aging population and rising social program costs -- that will cause headwinds when it comes to chipping away at its national debt.


8. Iceland -- Debt equals 98.2% of GDP


GDP: 1,630.15 billion Icelandic Kronurs ($13.85 billion)

Government Debt (Gross): 1,616.89 billion Icelandic Kronurs ($13.74 billion)

Iceland may already be known for its lush green landscapes, but the country is quickly becoming known for being in the red.

In 2008, Iceland's banks held an enormous amount of foreign assets and loans, totaling more than 10 times the country's GDP. After an unsustainable amount of bad loans and assets caused three of Iceland's largest banks to collapse, the country was forced to borrow $10 billion (nearly the size of its GDP) in loans from the IMF and other countries to bail out its financial sector, ensure that foreign deposits were guaranteed in the future and stabilize its currency.


7. Singapore -- Debt equals 100.8% of GDP


GDP: 326.832 billion Singapore dollars ($264.86 billion)

Government Debt (Gross): 331.118 billion Singapore dollars ($268.33 billion)

Singapore may rank seventh on this list, but not for the same reasons as other countries. In fact, it may surprise you that Singapore is actually considered a highly responsible country when it comes to fiscal matters.

Because the federal-debt-to-GDP ratio only takes into account the liabilities of a country and not that country's assets, Singapore is misrepresented as a debtor country.

It works like this: Singapore sells Treasury-bill-like debt securities to its citizens (called Singapore Government Securities or SGS) to raise cash. Instead of using that cash for spending, the government invests the capital in land and other safe investments, which is held in its Central Provident Fund (CPF) -- a pension fund for its citizens.

Singapore's safely held investment assets are more than enough to pay its obligations. This is why the Standard and Poor's (S&P) Rating Services has given Singapore a coveted AAA-credit rating on its ability to repay its long-term government debt.


6. United States -- Debt equals 102.9% of GDP


GDP: $15.094 trillion

Government Debt (Gross): $15.537 trillion

With the federal debt surpassing $15.5 trillion in 2011, the United States government holds the largest absolute amount of public debt in the entire world.

While some big-ticket items have certainly padded the debt load (including $900 billion on war spending and the $787 billion in stimulus spending in recent years, according to the CIA), it’s the ongoing spending that's the main driver of the national debt. According to a report by the Congressional Budget Office, the three largest federal program expenditures in the 2011 U.S. federal budget were: Social Security ($725 billion), defense ($700 billion) and Medicare ($480 billion).

In 2011, an astounding $227 billion (1.5% of GDP) in federal spending went toward the public debt's interest payments alone!

With an aging population, skyrocketing healthcare costs and dampened tax revenues from slow economic growth, the United States faces some real future challenges in reducing its federal debt and deficit if changes aren't made.


5. Ireland -- Debt equals 104.95% of GDP


GDP: 156.44 billion Euros ($220.12 billion)

Government Debt (Gross): 164.184 Euros ($231.02 billion)

Ireland hasn't had much luck in curbing its debt problem in recent years. The 2008 financial crisis brought on a devastating housing market bust (prices plummeted 47%), along with a series of large bank collapses.

Despite making severe cuts in federal spending, the government's obligation to fund its flailing banking sector in 2010 gave Ireland the largest federal budget deficit in the world that year -- amounting to a whopping 32.4% of GDP.

The bailout and the resulting budget deficit was so large, Ireland had to take out a $112 billion loan package from the European Union (EU) and IMF just to avoid defaulting altogether on its sovereign debt.

In 2011, Ireland faced a reduced-but-still-high budget deficit worth 10.1% of its GDP. As the country slowly heals, Ireland's debt continues to be watched closely by the European Union to prevent more complications in the euro-zone debt crisis.


4. Portugal -- Debt equals 106.8% of GDP


GDP: 171.68 billion Euros ($241.57 billion)

Government Debt (Gross): 183.33 billion Euros ($257.96 billion)

Weak or even negative economic growth in the past three years has kept Portugal from climbing out of its debt hole. Adding to the problem, Portugal's lack of a competitive labor force may keep the country's economy from growing much at all in the future.

While the government is planning to boost exports and improve its citizen's skills to improve economic growth, you can expect Portugal's tax revenues to remain depressed -- and its public debt levels high -- until those improvements actually come to fruition.


3. Italy -- Debt equals 120.1% of GDP


GDP: 1,580.22 billion Euros ($2.22 trillion)

Government Debt (Gross): 1,897.95 billion Euros ($2.67 trillion)

Italy's sizable economy (the third largest in the European Union) may not have been threatened by a real estate bust like many others, but that hasn't stopped it from racking up serious public debt.

Italy's inability to solve its debt and deficit problems stems from its shrinking economy. To this day, Italy's GDP is still 5% below its 2007 pre-crisis levels, and growth has been virtually stagnant for the past three years -- 0.4% in 2011, 1.3% in 2010 and -5.2% in 2009.

Adding to its long-term challenges, Italy's low fertility rate and strict immigration policies will cause headwinds against future economic growth, meaning its public debt will likely stay around for a while.


2. Greece -- Debt equals 160.8% of GDP


GDP: 217.81 billion Euros ($306.48 billion)

Government Debt (Gross): 350.26 billion Euros ($492.83 billion)

Anyone who has been paying attention to the euro-zone crisis is aware of Greece's dire financial situation.

Greece's expensive social entitlement programs (including healthcare and pension systems), the 2008 financial crisis and an economy that has been shrinking for the past four years have resulted in plummeting tax revenues and sky-high government deficits.

Greece's budget deficit peaked in 2009, amounting to a massive 15% of the country's GDP. Since then, Greece's government has taken action, but despite passing politically toxic and unpopular austerity measures -- draconian cuts in the federal budget, for example -- government budget shortfalls amounted to a still elevated 9% of GDP in 2011.

To help them cover those kinds of budget shortfalls and give the country more time to shore up its debt, the IMF and the EU granted Greece a second $169 billion bailout if the country promised more spending cuts and increased taxes. Greece can expect a painfully slow economic recovery -- expect the federal debt here to get worse before it gets much better.


1. Japan -- Debt equals 229.8% of GDP


GDP: 468,425 billion Yen ($5.879 trillion)

Government Debt (Gross): 1,076,315.29 billion Yen ($13.509 trillion)

Imagine a country that carries nearly the same amount of debt as America ($13.5 trillion) yet has an economy that produces less than half as much. That's debt-laden Japan.

After a stock market crash and banking crisis that happened nearly 20 years ago, Japan's economy has been mostly stagnant, and tax revenues simply haven't kept pace with government spending.

Criticizing Japan for being too 'leisurely' in controlling its debt, the Fitch Ratings agency recently downgraded Japan's credit rating to A+, from the original AA and AA- for long-term foreign and local currency issuer default ratings, respectively.

Though its situation may seem more dire, Japan is actually in better shape than Greece in some respects. Japan's economy (measured in GDP) is on track to grow 4.1% for 2012 -- twice as fast as the U.S. this year -- which may help increase tax revenues and shrink the country's deficit.

In addition, the CIA reports that less than 10% of Japan's federal debt is held by foreign countries and the vast majority is held by Japan's citizens through treasury bonds -- helping to protect the country from the political strife that's found between Greece and its neighboring euro-zone countries.