The average US price of regular-grade gasoline has plummeted 9 cents a gallon over the past two weeks to $3.58, the largest drop this year, a national survey finds.

Industry analyst Trilby Lundberg said Sunday the decrease came despite a rise in crude-oil prices.

The average US price of regular-grade gasoline has plummeted nine cents a gallon over the past two weeks

Trilby Lundberg says US refiners, enjoying plentiful supplies, aggressively cut wholesale prices to chase sales.

Mid-grade gas averages were $3.78, and premium averages were $3.93.

The US average retail diesel price is down 4 cents per gallon, to $3.90.

The lowest average price Trilby Lundberg found in the lower 48 states was $3.23 in Tulsa, Oklahoma. The highest was $4.03 in San Francisco.