WASHINGTON (AP) — Long-term U.S. mortgage rates fell this week to their lowest levels of the year. The benchmark 30-year rate dipped below the key 4 percent mark.

Mortgage buyer Freddie Mac said Thursday the average rate on 30-year fixed-rate home loans tumbled to 3.95 percent from 4.02 percent last week. The rate stood at 3.64 percent a year ago and averaged 3.65 percent in 2016, the lowest level in records dating to 1971.

The rate on 15-year mortgages slipped to 3.19 percent from 3.27 percent last week.

U.S. stock prices climbed for the sixth day in a row Thursday, following steep drops last week amid concern over political turmoil in Washington.

Absorbing the earlier market declines, bond prices rose this past week and pushed down yields on long-term Treasury bonds — which mortgage rates tend to follow.

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 unchanged this week at 0.5 point. The fee on 15-year loans also held steady at 0.5 point.

Rates on adjustable five-year loans dropped to 3.07 percent from 3.13 percent last week. The fee declined to 0.4 point from 0.5 point.