A national survey shows gas prices have dropped 15 cents a gallon in the last two weeks.

The average price of a gallon of regular gasoline at self-serve stations was $3.70 Friday. Mid-grade was at $3.83 and premium was at $3.95.

That's according to the Lundberg Survey of 7,000 gas stations nationwide, released Sunday.

Diesel was at $3.82.

The California average was $3.94, down 16 cents from two weeks ago.

Gas was cheapest in St. Louis, Mo., at $3.37 for a gallon of regular. It was most expensive in Anchorage, Alaska, at $4.34.

Despite the drop, gas nationally was almost 95 cents higher than a year ago.

Prices so far this summer peaked July 11 at $4.11 for a gallon for regular.

Click here to read the survey.