WASHINGTON (11/23/09)--Freddie Mac this week reported an average 30-year mortgage rate of 4.83 percent, the lowest mortgage rate of its type reported since the week ended May 21. Thirty-year mortgages averaged 6.04% during the same week of 2008 and 4.91% during through the end of last week. Fifteen year fixed rates, which averaged 4.32% during the week ended Nov. 19, were the lowest since Freddie Mac began tracking its weekly rates in 1991, Freddie Mac Vice President and Chief Economist Frank Nothaft said. “Low fixed rates throughout the third quarter prompted an estimated $1.1 trillion in refinancing activity, saving homeowners about $10 billion in aggregate monthly payments over the first 12 months of their new loan,” Nothaft added. Five-year and one-year Treasury-indexed hybrid adjustable-rate mortgages averaged 4.25% and 4.35%, respectively, during the week. Both rates represent slight decreases from the numbers reported during the previous week, and significant decreases from the rates reported during the corresponding period of 2008.