CAMARILLO, Calif. (AP) - An increase in crude oil supply has contributed to another drop in gas prices in the past two weeks, continuing a downward trend that began two months ago, an industry analyst said Sunday.

Between Dec. 3 and Dec. 17, the combined national price for all grades of gasoline dropped more than 10 cents per gallon to $1.86, bringing the total decrease since Oct. 22 to more than 21 cents per gallon, said analyst Trilby Lundberg, who publishes the semimonthly Lundberg Survey of 7,000 gas stations across the country.

As of Dec. 17, the average price at the pump for self-serve regular gasoline was $1.83, with mid-grade at $1.93 and premium at $2.02, she said.

Lundberg said a drop in seasonal demand, as well as a drop in crude oil prices from $55 a barrel to about $45 a barrel, helped ease pump prices just before the holidays. But prices are still "nearly 35 cents per gallon above what they were just before Christmas 2003," when the average price for self-serve regular was $1.48, Lundberg said.

The lowest average price for regular on Dec. 17 was in Tulsa, Okla., at $1.56 per gallon; the highest was in Honolulu, at $2.32.