California ? A national survey shows gas prices continue dropping across the nation.

The average price of a gallon of regular gasoline at self-serve stations was $3.85 Friday, down almost 15 cents from two weeks ago.

Mid-grade went for $3.98 and premium went for $4.10. That’s according to the Lundberg Survey of 7,000 gas stations nationwide, released Sunday. Diesel was at $4.64.

The cheapest gas was in Tulsa, Okla., where a gallon of regular cost $3.50. Anchorage, Alaska, was most expensive at $4.37. The Western states were the only region in the U.S. where gas remained above $4 a gallon on average.