Houses on the market last year in Larkspur, Calif. The Commerce Department announced that home sales unexpectedly fell in December for the first time since August. (Justin Sullivan/GETTY IMAGES)

Mortgage rates hit new historic lows this week, as the average 30-year fixed rate fell to 3.87 percent, according to Freddie Mac Mortgage Market Survey released Thursday.

The 30-year dropped this week after nudging up a bit last week to 3.98 percent, but overall the rate has remained below 4 percent for a couple months. Other rates hit new lows, including the 15-year, which fell to an average 3.14 percent, down 0.8 percentage points.

Compared to the same period a year ago, average 30-year fixed rate was 4.81 percent and the 15-year was 4.08 percent.

Rates dropped as the nation’s gross domestic product fell short of market projections, rising 2.9 percent in the final three months of 2011, according to Frank Nothaft, vice president and chief economist at Freddie Mac.

“One bright spot, however, was that fixed residential investment increased for the third consecutive quarter and residential construction spending rebounded in December, rising 0.7 percent,” Nothaft said.

Despite the low rates, not many homeowners can take advantage of them because they are underwater on their mortgage or do not qualify for refinancing under today’s tighter requirements.

President Obama announced new details of a proposal Wednesday to help more American homeowners take advantage of low interest rates through a refinancing program that would allow homeowners to refinance, saving an average of $3,000 a year. The plan, however, would require approval from Congress.

The administration also announced a pilot sale of foreclosed homes owned by Fannie Mae and Freddie Mac to investors, who would then agree to rent them out in a move aimed at boosting neighborhood home values and reducing the supply of foreclosed homes.

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