Interest rates on U.S. mortgage loans fell for the third straight week as economic data showed weaker prospects for the future, according to mortgage giant Freddie Mac Thursday.

“Long- and short-term mortgage rates fell for the third consecutive week amid continuing signs of a slowing economy,” said Frank Nothaft, Freddie Mac vice president and chief economist. “Retail sales fell for the fourth straight month in October and consumer sentiment remained near a 28-year low in November.

“In fact, the Federal Reserve during its October 28-29 committee meeting lowered its economic growth forecasts for 2008 and 2009, according to its minutes released this week.”

In response to such disheartening news, home loan lenders lowered their rates on 30-year fixed rate mortgages to an average of 6.04 percent, during the week ended Nov. 20, excluding points, down from 6.14 the previous week and 6.20 percent one year ago.

The average interest rate on 15-year fixed rate loans dropped to 5.73 percent from 5.81 percent the week before. At this time last year the average rate was 5.83 percent.

Rates on one-year adjustable rate mortgages averaged 5.29 percent, a decrease from 5.33 percent a week earlier and from 5.42 percent the previous year.

Freddie Mac complies its survey of weekly interest rates from roughly half of all lenders in the country. It is a “stockholder-owned corporation established by Congress in 1970 to provide liquidity, stability and affordability to the nation’s residential mortgage markets,” although recent financial crises have forced the federal government to place the company into a conservatorship. This government control period is designed to get the company operating on a financially-sound basis again and to make sure that mortgage money remains available for qualified borrowers.