WASHINGTON (AP) — U.S. long-term mortgage rates fell this week for the third straight week, as the benchmark 30-year loan marked its lowest point in three years.

Mortgage buyer Freddie Mac said Thursday the average rate for the 30-year fixed-rate mortgage declined to 3.45% from 3.51% last week. The key rate stood at 4.41% a year ago.

The average rate on a 15-year mortgage eased to 2.97% from 3% last week.

The historically low rates have been a boon for potential homebuyers. A positive outlook has come from signs of strength in the U.S. economy recently and expectations that the global economy could start to expand more quickly after being held back by trade conflicts.

Federal Reserve policymakers continued to hold interest rates low at their latest meeting last week. But the Fed chair warned that the viral outbreak in China poses a new threat to the strengthening global economy.

Freddie Mac surveys lenders nationwide between Monday and Wednesday each week to compile its mortgage rate figures. The average doesn't include extra fees, known as points, which most borrowers must pay to get the lowest rates.

The average fee on 30-year fixed-rate mortgages was unchanged from last week at 0.7 point. The average fee for the 15-year mortgage also remained at 0.7 point.

The average rate for a five-year adjustable-rate mortgage rose to 3.32% from 3.24% last week. The fee slipped to 0.2 point from 0.3 point.