The national price of gasoline remained essentially flat at $2.026 per gallon for the week ending Dec. 21, according to data from the U.S. Department of Energy.

The average price fell 1.1 cents for the week and is 37.7 cents lower that it was a year ago. Prices fell in six of the nine regions tracked by the agency's Energy Information Administration. Prices increased in the Lower Atlantic ($1.962), West Coast ($2.57) and West Coast without California ($2.283) regions. The sharpest decline came in the Central Atlantic with a 2.2-cent fall to $2.115.

Among states, Hawaii ($2.732) and California ($2.721) have gasoline costing more than $2 per gallon. Gasoline costs less than $2 in 29 states with Missouri's $1.774 price now the nation's lowest, accoring to AAA's Daily Fuel Gauge Report.

Meanwhile, the average price of diesel fell 5.4 cents to $2.284 per gallon. Diesel now costs 99.7 cents less than it did a year ago.