It's true that the U.S. has racked up the largest debt of any other developed country. But when you consider the debt in relation to the country's gross domestic product, it's only No. 7 on the list, according to Fortune.
Fueled by a high domestic savings rate, Japan has piled up debt to epic levels over the last few decades. But as its population ages and its national savings rate drops, the days of cheap debt are coming to an end -- and the global economy will feel the effects.