Australia's household debt is at its highest level in 25 years, increasing at twice the rate of growth of household assets. One saving grace, however, is that the rate of increase has slowed since the financial crisis.According to an Australian Bureau of Statistics report issued this week, the level of household debt at the end of 2013 was A$1.8 trillion, which is equivalent to $79,000 per person.Between 2001 and 2007 the rate of increase was 10 per cent a year. It slowed to two per cent a year between 2007 and 2013.Measured as a percentage of the value of household assets, household debt increased from just under 11 per cent in 1988 to almost 21 per cent at the end of 2011. It eased back to 20 per cent by the end of 2013.And measured as a percentage of income, household debt has grown from around 60 per cent of disposable income in 1988 to 100 per cent in 1999 and then 180 per cent at the end of 2013.The amount of interest households pay on debt peaked at 12 per cent of disposable income in 2008 and has since fallen back to seven per cent.An emerging problem for highly indebted households is the slowing of income growth. The ABS said disposable household income per person increased fairly steadily from 2002 to 2012 but since then has decreased slightly.The ABS said that the size of Australia's household debt compared with its income was not just high in historical terms; it is also high when compared with the household debt-to-income ratios of other G8 countries.Three-quarters of household debt is borrowing for housing.  The percentage of banks' domestic housing loans that were impaired (with payments overdue by 90 days or more) has come down from a peak of 0.9 per cent in 2011 to 0.6 per cent at the end of 2013.