
“A Home Affordability Index value of 100 means that a family with the median income has exactly enough income to qualify for a mortgage on a median-priced home. An index of 120 signifies that a family earning the median income has 20 percent more than the level of income needed pay the mortgage on a median-priced home, assuming a 20 percent down payment so that the monthly payment and interest will not exceed 25 percent of this level of income (qualifying income).”The higher the index, therefore, the more affordable homes are. Here is a graph showing the index since 1990:

