NEW YORK (CNN/Money) - Rates for long-term mortgages fell to new lows again this week as the Federal Reserve Board acknowledged weakness in the economy.

Freddie Mac reported Thursday that the 30-year mortgage averaged 6.22 percent in the week ending Aug. 16, with an average of 0.6 of a point payable up front to the lender. The rate dipped from an average 6.31 percent last week and remained lower than its average 6.92 percent a year ago. The new average 30-year rate breaks the 32-year low recorded last week.

The 15-year fixed-rate mortgage averaged 5.63 percent, down from 5.69 percent last week and down from 6.48 percent a year ago. The 15-year averaged 0.5 of a point payable up front. This rate is the lowest recorded since the company began tracking the 15-year rate about 15 years ago, according to Freddie Mac.

One-year adjustable-rate mortgages indexed to the Treasury averaged 4.39 percent, with an average 0.6 of a point due up front, up slightly from 4.37 percent last week and down from an average of 5.71 percent a year ago.

"The Fed's acknowledgement of weakness in the economy and a flight to quality in the bond market caused fixed-rate mortgage rates to slide further," Freddie Mac chief economist Frank Nothaft said. "And low mortgage rates certainly help offset rising home values, keeping houses affordable for a larger pool of homebuyers." (Read more about increasing the resale value of a home.)

Freddie Mac (FRE: up $0.29 to $64.17, Research, Estimates), or Federal Home Loan Mortgage Corp., is a publicly traded company the government established in 1970 to provide a flow of funds to mortgage lenders. It buys mortgages from banks, bundles them and then resells them as mortgage-backed securities.

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Its products, and the products of other similar entities, have become increasingly popular as an alternative to government-backed bonds, particularly with international investors.