WASHINGTON (AP) — Average long-term U.S. mortgage rates are down slightly this week and remain near historic lows.

Mortgage giant Freddie Mac says the national average for a 30-year fixed -rate mortgage slipped to 3.65 percent from 3.67 percent last week.

The average rate for a 15-year mortgage, popular with homeowners who refinance, slid to 2.92 percent from 2.94 percent.

A year ago, the 30-year mortgage rate averaged 4.33 percent; the 15-year mortgage averaged 3.39 percent.

The 30-year average rate hit a record low 3.31 percent in November 2012. The 15-year average hit bottom at 2.56 percent in May 2013.

Rates have remained low despite the Federal Reserve’s decision last year to stop monthly bond purchases meant to hold down long-term rates.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country at the beginning 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 a 30-year mortgage averaged 0.6 point this week, down from 0.7 point last week. The average fee for 15-year mortgage was 0.6 point, up from 0.5 point.

The average rate on a five-year adjustable-rate mortgage dropped to 2.84 percent from 2.88 percent last week, and the fee fell to 0.4 point from 0.5 point. For a one-year ARM, the average rate slipped to 2.44 percent from 2.46 percent last week; the fee was unchanged at 0.4 point.