The Mortgage Bankers Association said U.S. mortgage activity rose in the week ending Friday, as interest rates dropped. Mortgage activity increased 6.9 percent in the week. The trade group\'s Refinancing Index also rose, jumping 13.5 percent from the previous week. Interest rates for 30-year, fixed-rate conforming mortgages fell from 4.43 percent to to 4.36 percent with average points unchanged at 0.36. Rates for 15-year, fixed-rate contracts fell from 3.37 percent to 3.33 percent. Points for 15-year loans rose from 0.37 to 0.41.