WASHINGTON (AP) — Average long-term U.S. mortgage rates rose this week for the third straight week. Long-term rates have reversed the upward trend that took hold at the start of the year amid economic anxiety and market turbulence.

However, rates still remain at historically low levels at the start of the spring home buying season. Mortgage buyer Freddie Mac says the average rate on a 30-year, fixed-rate mortgage increased to 3.73 percent from 3.68 percent last week. The benchmark rate is closer to yet still below the 3.78 percent level it marked a year ago.

The average rate on 15-year fixed-rate mortgages rose to 2.99 percent from 2.96 percent last week.