CAMARILLO (AP) — The average U.S. price of a gallon of gasoline has increased 18 cents over the past two weeks.

The Lundberg Survey of fuel prices on Sunday put the average price for a gallon of regular at $3.69, about 8 cents higher than the same time last year.

Nationally, a gallon of mid-grade averages $3.84 and premium $3.96.

The price increase is due to the high cost of crude as well as the partial loss of production at a refinery in Northern California.

Tucson, Ariz., has the nation’s lowest price at $3.18, while Chicago had the highest at $4.23.

In California, the price rose 23 cents per gallon to an average $3.99 for regular.

Fresno had the lowest price, $3.83 for regular, and San Francisco had the highest, $4.06.

(© Copyright 2012 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)