Mortgage rates fell again this week, bringing the average rate on a 30-year fixed-rate loan farther below 5%, according to Freddie Mac's weekly survey of mortgage rates, released Thursday. The average 30-year fixed rate has dropped so rapidly that it is now lower than the average for a one-year adjustable loan. This is the first time the yield curve has been reversed since Freddie began collecting data for adjustable-rate mortgages in 1984. Mortgage rates have fallen in recent months, but many consumers are wary of making the commitment to purchase a home, and many prospective buyers face financing challenges in the tight credit market. Nevertheless, Frank Nothaft, vice president and chief economist at Freddie, said Thursday, "The housing market is showing further signs of possible improvement." He cited a report this week from the Federal Housing Finance Agency that showed "house prices rose for the second consecutive month in February, the first back-to-back increase since April 2007."