WASHINGTON — The average rate on a 30-year fixed- rate mortgage in the U.S. fell for a fourth straight week, according to Freddie Mac. Other rates also declined.

The rate slipped to 6.22 percent in the week ending yesterday from 6.26 percent last week. That compares with 5.81 percent a year ago. Freddie Mac, based in McLean, Virginia, is the second- biggest purchaser of U.S. mortgages. Fannie Mae is the largest.

Reports showing a drop in consumer and producer prices, along with signs that the housing market is slowing, drove borrowing costs lower. Long-term rates that are only about a percentage point above an all-time low will keep housing demand from plummeting, economists said.

"With mortgage rates edging back down in recent weeks, and evidence that price appreciation is losing momentum, we should see an orderly adjustment of the market to more reasonable sales rates and affordability levels in 2006," said Brian Bethune, an economist at Global Insight Inc.

The one-year adjustable rate declined to 5.15 percent from 5.22 percent, Freddie Mac said. The 15-year fixed rate fell to 5.76 percent from 5.79 percent.

Sales of existing homes dropped 1.7 percent to a 6.97 million annual rate, the National Association of Realtors said earlier today.

"We are starting to see a little bit of a slowdown in the enthusiasm for housing as an investment," said Amy Crews Cutts, deputy chief economist at Freddie Mac.

Mortgage rates move in synch with yields on U.S. Treasury notes, which have fallen on the view that increases in the Federal Reserve's overnight lending rate will curb inflation. The Fed on Dec. 13 raised its overnight lending rate to 4.25 percent, the 13th straight increase.

The yield on the 10-year Treasury note maturing November 2015 fell to 4.339 this week, the lowest since the end of September.

U.S. consumer prices fell by 0.6 percent in November, the largest decline since July 1949, because of a record drop in energy costs, the Labor Department said Dec. 15. Producer prices fell in November by the most since April 2003 as energy prices receded, a Dec. 20 government report showed.

"Lower figures for the recently released producer price index and consumer price index and lower, but still strong, gross domestic product, combined with the seasonal slowdown in the housing market, led to another decline in mortgage rates this week," Freddie Mac's Cutts said in a statement.

In a separate report, the National Association of Realtors said yesterday the number of previously owned homes on the market rose last month to the highest level in more than 19 years, while sales fell for the second-consecutive month, raising concerns that a housing bubble might be about to burst.

But many economists said the increase in homes for sale was actually a sign that the housing market was gradually cooling rather than threatening to implode.More than 2.9 million homes were on the market in the United States in November, the National Association of Realtors said.

That was up 14.3 percent from November 2004, and the highest level since April 1986.