Gasoline prices continued their upward climb, rising 5.3 cents to $2.744 for a gallon of unleaded as a national average, according to the U.S. Department of Energy.

The average national price for the week ending May 18 is now 92.1 cents lower than it was a year ago. Prices increased incrementally across the nine regions tracked by the agency with the sharpest increase coming in the Midwest at 8.9 cents to $2.597. The highest price remains on the West Coast at $3.513.

Among the states, California remains the costliest state for gasoline purchases with an average price of $3.803 per gallon. Six other states have an average price above $3, including Nevada, Hawaii, Alaska, Oregon, and Washington. Ten states have gasoline that costs less than $2.50 per gallon with South Carolina's $2.413 now the cheapest state average.

Meanwhile, the average price of diesel rose 2.6 cents to $2.904 per gallon. Diesel now costs $1.03 less than a year ago.