WASHINGTON (AP) — Average U.S. mortgage rates rose slightly this week, but the benchmark 30-year rate stayed near a 19-month low.

Mortgage giant Freddie Mac says the nationwide average for a 30-year fixed rate mortgage increased to 3.87 percent this week, up from 3.83 percent last week. The rate hit 3.80 percent earlier this month, lowest since May 2013.

The average for a 15-year mortgage also rose — to 3.15 percent this week from 3.10 a week earlier. The rate for a one-year adjustable-rate mortgage blipped up to 2.40 percent from 2.39 percent last week.

A year ago, the 30-year mortgage stood at 4.53 percent and the 15-year mortgage at 3.55 percent. Mortgage rates have remained low even though the Federal Reserve in October ended its monthly bond purchases, which were meant to keep long-term rates low.

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 was 0.6 point, unchanged from last week. The fee for a 15-year mortgage was also unchanged at 0.6 point. The fee for a one-year ARM also was unchanged at 0.4 point.

The average rate on a five-year adjustable-rate mortgage stayed at 3.01 percent; the fee was also unchanged at 0.5 point.