Mortgage rates haven't risen this consistently to start a year in more than 40 years, according to Freddie Mac’s latest Primary Mortgage Market survey.

“Mortgage rates so far in 2018 have had the most sustained increase to start the year in over 40 years,” Freddie Mac Chief Economist Sam Khater noted in the report. “Through May, rates have risen in 15 out of the first 21 weeks (71%), which is the highest share since Freddie Mac began tracking this data for a full year in 1972.”

Freddie Mac May 24

(Source: Freddie Mac)

According to the report, the 30-year fixed-rate mortgage increased to 4.66% for the week ending May 24, 2018, up from 4.61% last week and 3.95% last year.

The 15-year FRM increased to an average 4.15% this week, up from 4.08% last week and 3.19% last year.

The five-year Treasury-indexed hybrid adjustable-rate mortgage increased to an average 3.87% this week, up from 3.82% last week and 3.07% last year.

“At a time when housing inventory remains extremely low, it’s worth watching whether these higher borrowing costs lead some would-be sellers to stay put in their current home.”  Khater said. “Inventory shortages would likely worsen if more homeowners decide not to sell out of reluctance of having a new mortgage with a higher rate.”