AAA: Gas below $2 per gallon in 18 states

U.S. consumers are paying an average price of $2.13 per gallon of gasoline, a forty percent decrease from last year's peak, according to AAA.

The average price of gas across the U.S. is the lowest it has been since 2009. Monday's price was seven cents less than one week ago, AAA said.

"Motorists in 11 more states saw their average price at the pump drop below $2 per gallon over the past week, bringing the total number of states below this threshold to 18," AAA said in its fuel report on Monday.

As many as 25 states could see the price of gas fall below $2 per gallon by next week, AAA said.

The steep drop in the price of crude oil is credited for the low gas prices in the U.S.

The price of oil has lost over half of its value since mid-2014.