WASHINGTON >>The average U.S. rate on a 30-year fixed mortgage fell this week to a record low for the seventh time in eight weeks. Cheap mortgages have helped drive a modest recovery in the weak housing market this year.

Mortgage buyer Freddie Mac said today that the average on the 30-year loan dropped to 3.66 percent. That’s down from 3.71 percent last week and the lowest since long-term mortgages began in the 1950s.

The average rate on the 15-year mortgage, a popular refinancing option, declined to 2.95 percent. That’s down from 2.98 percent last week and just above the record 2.94 percent reached two weeks ago.

The rate on the 30-year loan has been below 4 percent since December.