The average 30-year U.S. mortgage rate decreased this week, providing positive news for homebuyers during the spring buying season. Freddie Mac reported the average slipped to 6.60% from 6.73% the previous week. In February, the Federal Reserve raised its benchmark lending rate by 25 basis points, which marked the eighth increase in less than a year, bringing the key rate to its highest level in 15 years. The big increase in mortgage rates over the past year has battered the housing market, as existing home sales fell by 37% in January.