WASHINGTON >> Long-term U.S. mortgage rates climbed for the fifth straight week amid investors’ growing concern about inflation.

Mortgage giant Freddie Mac said Thursday the average rate on 30-year, fixed-rate mortgages shot up to 4.32 percent this week, up from 4.22 percent last week and the highest since December 2016. A year ago, it stood at 4.17 percent.

The rate on 15-year, fixed-rate loans, popular among homeowners who refinance, rose to 3.77 percent from 3.68 percent last week and the highest since May 2011. It was 3.39 percent a year ago.

A strong U.S. economy is raising fears that inflation may be on the rise; investors are demanding higher interest rates. The yield on 10-year Treasury notes, which influences mortgage rates, has risen the past week to 2.88 percent from 2.78 percent.

“Will higher rates break housing-market momentum? It’s too early to tell for sure,” said Len Kiefer, a Freddie Mac economist. He noted that applications to buy homes are still up 8 percent from a year ago.

The rate on five-year adjustable rate mortgages rose to 3.57 percent this week from 3.53 percent last week and the highest since April 2011. It was 3.21 percent a year ago.

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 fee on 30-year loans blipped up to 0.6 point from 0.5 point last week. The fees were all unchanged at 0.5 point for 15-year mortgages and 0.4 point for five-year adjustable mortgages.