WASHINGTON (AP) — Long-term U.S. mortgage rates fell this week, offering a slight degree of relief to would-be homebuyers.

Mortgage buyer Freddie Mac said Thursday that the average rate on 30-year, fixed-rate mortgages dropped to 4.52 percent from 4.55 percent a week ago. Rates have declined in five of the past six weeks. Still, the average rate has increased from a year ago when it stood at 3.96 percent.

The average rate on 15-year, fixed-rate loans slipped to 3.99 percent from 4.04 percent a year ago.

Mortgage rates have declined as investors have bought 10-year U.S. Treasury notes, causing their yield to decline. The yield peaked in May at 3.11 percent and has since dipped to 2.83 percent as the financial markets have sought a haven amid risks of a trade war.

Despite the recent declines, long-term loan rates remain near their highest levels in seven years. The average 30-year mortgage rate reached a high this year of 4.66 percent on May 24; the 15-year rate hit 4.15 percent that day.

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. The average fee on 30-year fixed-rate mortgages was unchanged from last week at 0.5 point.