U.S. demand for gasoline averaged 6.9 million barrels per day in May, down 1.6% from the 7-million average in May, 1985, the American Petroleum Institute said. The May decline probably reflects inventory changes rather than an actual drop in consumption, the institute said. Retail prices in May were down about 25% from year-ago levels, the institute said. In another report, motorists willing to pump their own gasoline are paying less than 90 cents a gallon, and prices will continue to fall this week in an unprecedented Fourth of July holiday drop, according to oil analyst Dan Lundberg. The latest Lundberg Survey found that the average price of regular leaded gasoline at self-serve pumps, including all taxes, is now 82.95 cents per gallon. Regular unleaded is 88.70 cents per gallon and premium unleaded is 102.50 cents.