The average rate for a 30-year fixed-rate mortgage fell to 4.28% in the week that ended March 6 from 4.37% in the prior week, according to a Thursday report from federally controlled mortgage buyer Freddie Mac. A year ago, the 30-year rate was at 3.52%. The average rate for the 15-year fixed-rate mortgage fell to 3.32% in the latest week from 3.39% in the prior week. Meanwhile, the rate for a 5-year Treasury-indexed hybrid adjustable-rate mortgage declined to 3.03% from 3.05%. The rate for a 1-year Treasury-indexed ARM was unchanged at 2.52%.