U.S gasoline pump prices declined 2.5 cents a gallon over the last week to a new five-week low average of $1.679, the Energy Department said on June 4. Gasoline prices rose the previous week to above $1.70 a gallon on average, but the latest government measure puts prices back on a downward track. The fuel price is based on the Energy Information Administration's weekly survey of 800 service stations nationwide. The price for reformulated gasoline, the cleaner-burning fuel sold at about one-third of the nation's pumps, decreased 1.9 cents a gallon this past week to $1.791 a gallon, according to the Energy Department. The department's statistical agency has predicted the national average price for regular unleaded gasoline could climb as high as $1.75 a gallon this summer. Below-average gasoline supplies, strong consumer demand and costly crude oil have kept prices high at the pump, according to analysts.