Retail gasoline prices are expected to average $1.56 a gallon during the summer (April through September), according to a recent report by the Energy Information Administration (EIA), a statistical agency of the U.S. Department of Energy. The forecast should provide some welcome relief for fleets burdened by skyrocketing fuel costs due to recent price surges at fuel pumps across the country. The national average price of gasoline hit as high as $1.73 a gallon in March, according to EIA price data, and topped $2 a gallon in some parts of the country. Although down from recent highs, the projected summer average is up 17 cents a gallon from the previous summer, but is near average summer prices in 2000 and 2001. The agency, which tracks national average fuel prices and other energy-related data, cautioned that continued uncertainty in the world markets could affect the forecast and cause prices to rise again.