WASHINGTON — U.S. average rates on long-term mortgages fell this week, with historically low levels continuing to fuel demand for homes.

Mortgage buyer Freddie Mac reported today that the average rate on the 30-year home loan declined to 2.91% from 2.99% last week. By contrast, the rate averaged 3.58% a year ago.

The average rate on the 15-year fixed-rate mortgage fell to 2.46% from 2.54% last week.

Housing demand continues as one of few bright spots in the pandemic-hobbled economy, especially for prospective buyers considering a first-time purchase. The trend may even extend strong sales of homes, which has already carried over from spring into summer, further into the fall, Freddie Mac says.

Homeowners looking toward refinancing mortgages gained a reprieve this week on a new fee approved by the federal regulator of Freddie and its larger government-controlled sibling Fannie Mae. The fee for lenders, equivalent to half a percent of the total home loan, was delayed from taking effect on Sept. 1 to Dec. 1.

The fee is intended to provide a cushion for Fannie and Freddie against possible mortgage defaults in the severe economic downturn. It’s likely to be passed on to homeowners and is expected to cost an average of around $1,400 — prompting objections by mortgage lenders and consumer advocates.