One reason the Reserve Bank wants banks to maintain prudent lending standards is that the proportion of households with mortgages has increased over the long term. Another is that the average level of mortgage debt has increased at a faster rate than residential property values.Since the financial crisis, households have reduced personal debt, made extra payments on their mortgages and increased their savings.But long-term surveys by the Australian Bureau of Statistics and the Melbourne Institute tell a different story. More households are carrying more mortgage debt.According to an ABS study published last month, Housing Occupancy and Costs, the proportion of Australian households that own their home outright fell from 42 per cent in 1994/95 to 31 per cent in 2011/12.Over the same period, the proportion of households with a mortgage rose from 30 to 37 per cent and the proportion renting rose from 18 to 25 per cent.Melbourne Institute's latest household survey, Household, Income and Labour Dynamics in Australia, which was published earlier this year, found that over the period 2001 to 2010 the median house price increased 86 per cent, from $259,000 to $482,000 (the report presents all dollar values in 2010 prices to remove the effect of inflation). The mean (average) house price rose 67 per cent, from $341,000 to $569,000. Mean home equity (the value of the home minus debt on the home) rose 60 per cent over that period, from $255,000 to $408,000. In other words, home debt grew at a faster rate than home value over the years between 2001 and 2010.The HILDA survey found that the percentage of households with negative home equity (mortgage debt that exceeds the value of the home) rose from 1.7 per cent in 2001 to 2.6 per cent in 2010.And the Westpac Home Ownership report, published last month, showed that a significant number of households are still repaying debt in what would normally be considered the retirement years. The peak borrowing years are 35 to 44, when 53 per cent of people have a home loan. Among people over 65, fourteen per cent are still paying off a home loan.