Mortgage application volumes increased 7.2% in the week ended March 31 compared to the prior week, data from the Mortgage Bankers Association show. Also on a seasonally adjusted basis, applications for mortgages to buy homes jumped 8.4%, while the week-to-week growth in refinancing applications was 5.3%. Refinancings accounted for 36.6% of total applications last week, down from 37.3% a week earlier, while adjustable-rate mortgages slipped to 28.5% from 28.7%. Refinancings thus accounted for the lowest proportion of total applications since the final week of July 2004, the MBA said. Average contract interest rates for 30- and 15-year fixed-rate mortgages rose last week to 6.49% and 6.15%, respectively, from 6.36% and 6.00% a week earlier. One-year ARMs averaged 5.96%, up from 5.83%. The MBA's four-week moving average tracking seasonally adjusted mortgage applications was up 1.6%