(Undated) – Gas prices continue to show the effects of seasonal trends. According to this morning’s numbers from GasBuddy.com, the national average is two cents higher than the beginning of the week at $3.09 a gallon. Here in Illinois, the statewide average is $3.19 a gallon, down five cents from the beginning of the week. Across the Wabash in Indiana, the statewide average is $2.93 a gallon, down eight cents from Monday. Oklahoma has the lowest prices in the nation at $2.55 a gallon. California has the highest statewide average at $4.48.