Freddie Mac’s weekly rate report said the average 30-year, fixed-rate mortgage fell to 4.78 percent, matching a low set April 7. It is the lowest rate on such mortgages since Freddie Mac started keeping track in 1970.

Adjustable-rate mortgages also eased, but one-year, adjustable-rate mortgages are averaging rates nearly the same as 30-year fixed rates, at 4.77 percent.

Freddie Mac said borrowers who refinanced their mortgages in the first quarter reduced their combined mortgage payments by about $2.5 billion over the coming year.