The average price of a gallon of self-serve regular  gasoline in the Inland Empire dropped Wednesday by its largest amount since Dec. 19, falling one cent to $4.25.
      The average price in Riverside and San Bernardino counties has declined  for six consecutive days and is three cents less than one week ago and 10 cents  less than one year ago, but 23.5 cents more than one month ago, according to  figures from the AAA and Oil Price Information Service.
      The dropping prices are the result of decreasing prices for oil and  gasoline futures caused by an increase in fuel supplies stemming from increased refinery production, according to Jeffrey Spring of the Automobile Club of Southern California.