Rates on a 30-year fixed mortgage dropped to 5.19% this week, after the Fed slashed interest rates to historic lows.

NEW YORK (CNNMoney.com) -- Mortgage rates fell this week, with the 30-year fixed mortgage sinking to its lowest rate in 37 years as the Federal Reserve cut interest rates to historic lows.

Government-sponsored mortgage lender Freddie Mac (FRE, Fortune 500) said Thursday that fixed rates on 30-year mortgages averaged 5.19% for the week ending Dec. 18. That's down from 5.47% last week and below the year-ago rate of 6.14%.

"Interest rates for 30-year fixed-rate mortgage rates fell for the seventh consecutive week, moving these rates to the lowest since the survey began in April 1971," said Frank Nothaft, Freddie Mac vice president and chief economist.

"The decline was supported by the Federal Reserve announcement on December 16th, when it cut the federal funds target to a record low and stated it stood ready to expand its purchases of mortgage-related assets as conditions warrant."