The disparity between San Diego’s housing prices and the national average — San Diego’s being greater — is growing and won’t lessen anytime soon, according to a recent study by the National University System Institute for Policy Research.

“We’re going back into that territory where we are one of the least affordable markets in the United States, and it seems to be getting worse,” said Kelly Cunningham, the private think tank’s economist and author of the report.

While housing prices have risen throughout the nation after the bubble burst beginning in 2009, the increase locally has pushed beyond a point that exceeds the incomes of most San Diegans. Only 37.1 percent of the properties sold during the second quarter of the year were affordable to those earning the county’s median family income of $72,300, the report said, citing data in the National Association of Home Builders’ housing opportunity index.

That low percentage made San Diego the eighth least affordable market in the nation, though not as unaffordable as a few other California cities. San Francisco was ranked least affordable, with 19.3 percent of properties sold deemed affordable to median-income families, even though its median family income was $101,200.

It was followed by the Los Angeles and Orange County areas at about 28 percent. Indeed, California was home to 13 of the 15 least affordable markets in the nation, with the New York City and Bridgeport-Stamford, Conn., areas being the only markets outside California among the 15 least affordable.

Nationwide, 69 percent of the houses sold in the second quarter were affordable to those earning the family median income of $64,400, the report said.

Looking at the data another way, Cunningham noted, a median-priced home in San Diego — $400,000 in the second quarter — equates to 5.53 times the area’s median income. That compares with the national median price-to-income ratio of 3.14.

The local market’s median price-to-income ratio bottomed out at 3.5 in the mid-1990s. It then rose fairly steadily to nearly 8 in 2005 before the bubble burst and it fell to 3.6 in 2009, said the report from NUSIPR.

Paying Higher Percentage of Income

Combined with the area’s rising house prices is the fact that the median income fell nearly 5 percent from last year when it reached nearly $76,000.

Not surprisingly, San Diego residents pay a disproportionate part of their incomes on housing. Citing a study from the National Center for Policy Analysis, local homeowners earning the median income spend about 35 percent of that for housing. That compares with Dallas residents who have a lower median income but spend only 15 percent on housing, the report said.