Gas prices drop again

(CNN) - Gas prices dropped a little more than 15 cents in the past two weeks, the publisher of a national survey said Sunday.

The latest Lundberg Survey, carried out on Friday, found an average price of $3.70 for a gallon of self-serve regular.

The survey tallies prices at thousands of gas stations across the nation.

Publisher Trilby Lundberg attributed the fall to the drop in demand and the fact that gas refiners and retailers did not pass on higher expenses to their customers.