Think US debt is high? Take a look at Europe's most indebted nations.

In April, the IMF estimated that the US government's debt amounted to 99 percent of gross domestic product. That’s high, but less than four of Europe's five largest debtors.

3. Ireland

Ireland’s fall from its economic pedestal was as dramatic as Iceland’s. It was in a period of booming growth, earning the nickname of the “Celtic Tiger,” until its economy screeched to a halt in early 2009. It reluctantly agreed to a bailout from the EU in December 2010 that came hand-in-hand with an austerity budget meant to chip away at its mounting debt.

Reuters reports that Ireland’s efforts to get its house in order have been successful and that it enjoys much more confidence from investors than other bailout recipients as a result – but it has yet to rein in its debt, which is expected to continue climbing. In April, Ireland’s public debt stood at 114 percent of its GDP, and it is expected to hit 125 percent in 2013.

3 of 5