WASHINGTON (AP) — Average long-term U.S. mortgage rates were flat to slightly lower this week, remaining near their highest levels so far this year.

Mortgage giant Freddie Mac says the average rate on a 30-year fixed-rate mortgage was unchanged from a week earlier at 3.87 percent. The rate on 15-year fixed-rate mortgages slipped to 3.08 percent from 3.11 percent.

Despite their climb in recent weeks during the height of the spring home buying season, mortgage rates remain low by historic standards. A year ago, the average 30-year rate was 4.14 percent and the 15-year was 3.23 percent.