Updated

Retail gas prices continue to plunge across the country, dropping 18 cents in the past two weeks, according to a survey released Sunday.

The weighted average price for all three grades declined to $2.27 a gallon on Nov. 18, said Trilby Lundberg, who publishes the semimonthly Lundberg Survey of 7,000 gas stations around the country.

Self-serve regular averaged $2.24 a gallon nationwide. The price for midgrade was $2.34, while premium-grade hit $2.44.

The lowest average price in the nation for regular unleaded among the stations surveyed was $1.94 a gallon in Wichita, Kan. The highest price was $2.64 in Honolulu.