After dropping to less than $2 per gallon last month, the national average price of a gallon of gas is rising again, in large part because of higher crude oil (search) prices, an industry analyst said Sunday.

Between Oct. 8 and Friday, the combined national average price for all grades of gas rose from $2.02 to $2.07 per gallon, said Trilby Lundberg (search), who publishes a semimonthly survey of gas stations across the country.

The biggest-selling grade of gas, self-serve regular, was pegged at $2.04. Premium grade was priced at $2.23 a gallon, and mid-grade at $2.14.

San Diego (search) led the nation with an average price for a gallon of self-serve regular at $2.45. The best bargain was Tulsa, Okla., where the average price for self-serve regular was $1.83.

Fears about supply from top oil-producing countries and the growing appetite of emerging economic powers like China and India have helped push up crude oil prices about 80 percent from a year ago.

That has sent U.S. pump prices on a roller-coaster ride.

Lundberg said the national average price for all grades combined was $1.51 in December, then it climbed to $2.10 by late May. The average price dropped off to $1.88 by mid-September, then began climbing again.