Mortgage applications jump on refi demand: MBA NEW YORK (Reuters) - Applications for home mortgages jumped last week, fueled by increased demand for refinancing as interest rates fell, an industry group said on Wednesday. The Mortgage Bankers Association said its seasonally adjusted index of mortgage application activity, which includes both refinancing and home purchase demand, rose 7.5 percent in the week ended Feb 3. The MBA's seasonally adjusted index of refinancing applications climbed 9.4 percent, while the gauge of loan requests for home purchases was nearly flat, edging up just 0.1 percent. The refinance share of total mortgage activity also increased to 80.5 percent of applications, from 80.0 percent. Fixed 30-year mortgage rates averaged 4.05 percent, down 4 basis points from 4.09 percent the week before. The survey covers over 75 percent of U.S. retail residential mortgage applications, according to MBA. Reporting By Leah Schnurr; Editing by Leslie Adler