The average U.S. rate on the 30-year fixed mortgage was unchanged this week near historic lows, while the average rate on the 15-year loan fell. Low mortgage rates could help strengthen the housing recovery.

Mortgage buyer Freddie Mac said Thursday that the rate on the 30-year loan stayed at 3.53 percent. That's still near the 3.31 percent rate reached in November, the lowest in records dating to 1971.

The rate on the 15-year fixed mortgage dropped to 2.77 percent from 2.81 percent last week. The record low is 2.63 percent.

Cheap mortgages are encouraging more people to buy homes and refinance, trends that could help boost the economy this year.

Increased sales are helping push home prices up steadily, which makes consumers feel wealthier and more likely to spend. In addition, a limited supply of houses for sale has created demand for new construction, which has made builders more confident.

And when people refinance, that typically leads to lower monthly mortgage payments and even more spending. Consumer spending drives nearly 70 percent of economic activity.

Still, the housing market has a long way to a full recovery. And many people are unable to take advantage of the low rates, either because they can't qualify for stricter lending rules or they lack the money to meet larger down payment requirements.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country on Monday through Wednesday of each week. The average doesn'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 30-year loans ticked up to 0.8 point from 0.7 point last week. The fee for 15-year loans was unchanged at 0.7 point.

The average rate on a one-year adjustable-rate mortgage fell to 2.53 percent from 2.59 percent. The fee for one-year adjustable-rate loans declined to 0.4 from 0.5 point.

The average rate on a five-year adjustable-rate mortgage fell to 2.63 percent from 2.70 percent last week. The fee remained at 0.6 point.