Adecade ago, American consumers seemed the most debt-addicted people on the planet. Since 2008, however, something rather remarkable has occurred: the level of consumer card and mortgage debt in the US has shrunk.

But there is one glaring exception to this trend: student debt. Over the past decade, the level of outstanding student debt has almost tripled to $1.3tn.

And although the law makes it relatively hard to walk away from student debt, defaults are also strikingly high. There are many ways to measure this figure but the Department of Education reports that Americans who were due to start repaying their student debts in 2011 had a 13.7 per cent default rate last year. This is a touch lower than the previous year (14.7 per cent) but dramatically higher than it had been since the mid-1990s; and it is higher than the credit card default rate.