U.S. mortgage demand falls in Aug 15 week-MBA Wednesday August 20, 7:30 am ET NEW YORK, Aug 20 (Reuters) - The Mortgage Bankers Association of America (MBA) weekly mortgage application survey for the week ended Aug 15: . Market Composite Index (seasonally adjusted) . Latest Previous Pct 4 Weeks 1 Year . Week Week Change Ago Ago . ------------------------------------ Market Index 736.7 824.6 -10.7 1284.3 1127.4 Purchase Index 389.5 409.6 -4.9 442.4 371.6 Refinancing Index 2756.8 3238.4 -14.9 6181.2 5523.6 Fixed-rate Index 591.8 669.3 -11.6 1120.8 1022.8 Adjustable-rate 3770.8 4076.0 -7.5 4706.3 3318.0 Conventional Market Indices (seasonally adjusted) Conventional Index...