WASHINGTON — Fixed mortgage rates fell once again to a record low, offering a great opportunity for those who can afford to buy or refinance homes. But few are able to take advantage of the historic rates.

Freddie Mac said Thursday the average rate on the 30-year fixed mortgage fell to 3.89 percent. That's below the previous record of 3.91 percent reached three weeks ago.

Records for mortgage rates date back to the 1950s.

The average on the 15-year fixed mortgage ticked down to 3.16 percent. That's down from a record 3.21 percent three weeks ago.

Mortgage rates are lower because they track the yield on the 10-year Treasury note, which fell below 2 percent. They could fall even lower this year if the Fed launches another round of bond purchases, as some economists expect.

Average fixed mortgage rates hovered around 4 percent at the end of 2011. Yet many Americans either can't take advantage of the rates or have already done so.

High unemployment and scant wage gains have made it harder for many people to qualify for loans. Many don't want to sink money into a home that they fear could lose value over the next few years.

Previously occupied homes are selling just slightly ahead of 2010's dismal pace. New-home sales in 2011 will likely be the worst year on records going back half a century.

Builders are hopeful that the low rates could boost sales next year. Low mortgage rates were cited as a key reason the National Association of Home Builders survey of builder sentiment rose in December to its highest level in more than a year.

But so far, rates are having no major impact. Mortgage applications have fallen slightly on a seasonally adjusted basis over the past four weeks, according to the Mortgage Bankers Association.

To calculate the average rates, Freddie Mac surveys lenders across the country Monday through Wednesday of each week. The average rates don't include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for the 30-year loan fell to 0.7 from 0.8; the average on the 15-year fixed mortgage was unchanged at 0.8.

For the five-year adjustable loan, the average rate declined to 2.82 percent from 2.86 percent. The average on the one-year adjustable loan fell to 2.76 percent from 2.80 percent.

The average fee on the five-year adjustable loan rose was unchanged at 0.7; the average on the one-year adjustable-rate loan was unchanged at 0.6.

The Associated Press reports that a proposed deal could be announced within weeks. Five banks—Bank of America, JPMorgan Chase, Wells Fargo, Citibank and Ally Financial (formerly GMAC)—would pay the federal government $25 billion. About $17 billion would be used to reduce the principal that some struggling homeowners owe, $5 billion more would be used for future federal and state programs and $3 billion would be used to help homeowners refinance at 5.25 percent. Civil immunity would be granted to the banks for any role in foreclosure fraud, and there would be no investigations.