The average 30-year U.S. mortgage rate this week remained at a 52-week low of 4.10 percent for the third straight week.

Mortgage company Freddie Mac also said Thursday the average for a 15-year mortgage, a popular choice for people who are refinancing, slipped to 3.24 percent from 3.25 percent.

At its 52-week low of 4.10 percent, the rate on a 30-year mortgage is down from 4.53 percent at the start of the year. Rates have fallen even though the Federal Reserve has been trimming its monthly bond purchases, which are intended to keep long-term borrowing rates low. The purchases are set to end in October.

The low rates appear to have boosted U.S. home sales. Also, moderating increases in home prices such as occurred in July should help support sales by making homes more affordable. Real-estate data provider CoreLogic reported Tuesday that home prices rose in July but at a slower rate compared with earlier this year.

Greater affordability has helped the housing market recover over the spring and summer after sales and construction fell earlier this year. Sales of existing homes rose for a fourth straight month in July to their strongest pace in nine months. And a measure of signed contracts also increased in July, suggesting that final sales will rise further in coming months.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country between Monday and Wednesday 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 a 30-year mortgage was 0.5 point, unchanged from last week. The fee for a 15-year mortgage fell to 0.5 point from 0.6 point.

The average rate on a five-year adjustable-rate mortgage was stable at 2.97 percent. The fee stayed at 0.5 point.

For a one-year ARM, the average rate edged up to 2.40 percent from 2.39 percent. The fee dipped to 0.4 point from 0.5 point.

(AP)