RIVERSIDE, Calif. -

The average price of a gallon of self-serve regular gasoline in the Inland Empire fell Wednesday for the 13th consecutive day after rising 30 times in 31 days, dropping 1.2 cents to $4.197.
      The average price is 6.2 cents less than one week ago and 18.2 cents  lower than one year ago, but 4.4 cents more than one month ago, according to  figures from the AAA and Oil Price Information Service.
      Most California refineries have concluded their scheduled maintenance  without any major incidents before switching to producing summer blend  gasoline, thereby ensuring adequate supplies, Jeffrey Spring of the Automobile  Club of Southern California said in explaining why both wholesale and retail  prices have been dropping.