WASHINGTON (AP) — The average rate on the 30-year fixed mortgage stayed at a record low this week, providing some added incentive for those looking to buy a home or refinance.

Mortgage buyer Freddie Mac said Thursday the rate on the 30-year loan was unchanged at 3.87 percent. That's the lowest level on records dating back to the 1950s.

The average on the 15-year fixed mortgage rose to 3.16 percent, up from last week's record low of 3.14 percent.

Still, low rates have done little to boost the struggling housing market. Rates have been below 5 percent for all but two weeks in the past year. Yet few people can qualify to buy a home or refinance. Many of those who can have already done so.

And some prospective buyers don't want to put money into a home that they fear could fall in price over the next few years.

Sales of previously occupied homes were dismal last year. New-home sales in 2011 were the worst on records going back half a century.

Builders are hopeful that the low rates could boost sales this year. But so far, they have had a minimal impact.

To calculate the average rates, Freddie Mac surveys lenders across the country Monday through Wednesday of each week.

The average rates don't include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for the 30-year loan was unchanged at 0.8; the average on the 15-year fixed mortgage dipped to 0.7 from 0.8.

For the five-year adjustable loan, the average rate rose to 2.83 percent from 2.80 percent, and the average fee was unchanged at 0.7.

The average on the one-year adjustable loan rose to 2.78 percent from 2.76 percent, and the average fee was unchanged at 0.6.