Household Debts Ratio Are Lowest Since 1990s

The chart above displays Federal Reserve data on: a) the quarterly household debt service ratio (red line), which is the ratio of debt payments to disposable personal income. Debt payments consist of the estimated required payments on outstanding mortgage and consumer debt; and b) the quarterly financial obligations ratio, which adds automobile lease payments, rental payments on tenant-occupied property, homeowners' insurance, and property tax payments to the debt service ratio (blue line).

The debt service ratio was 11.75% in the last quarter of 2010, which is the lowest ratio since the first quarter of 1998,  and the financial obligations ratio at 16.64% in Q4 2010 was the lowest since the first quarter of 1995.  

Explanations?  Thoughts?