15 very affordable metros, where less than 15% of income buys a house

The financial rule of thumb is well known by now: No more than 36 percent of your income should go toward paying debts, and of that, no more than 28 percent of your income should go toward mortgage or rent expenses.

In the Dallas-Fort Worth metro area, just 11.2% of the median income is needed to afford the purchase of a median …

For the beaten-down residents of the nation's least affordable housing markets -- including your friends here at California-based Yahoo Homes -- that can seem almost laughable. During the 15 years before the housing bubble started inflating (1985 to 1999), a Los Angeles homeowner earning the local median income needed to devote more than 35 percent of that paycheck to mortgage expenses just to afford a median-priced home in the area. And right now? That figure is a staggering 43 percent in L.A., and in San Francisco too.

That's why we were surprised to discover in a recent Zillow study that just 15 percent of the national median income is enough money to afford the purchase of a median-priced home. (Historically that ratio has been about 22 percent.)

Furthermore, Zillow identified 15 metro areas where even less of the local median income is plenty to buy a home.

Low mortgage rates get most of the credit for keeping for-sale homes so historically affordable, Zillow said, cautioning that those rates are expected to rise in the coming year.

Renters, meanwhile, are facing a crushing market in which 29.5 percent of their income goes to housing, compared with 25 percent before the bubble.