Gas prices in Lincoln have fallen about a penny a gallon the past week, averaging $3.72 a gallon on Sunday. National, the average price has increased more than 2 cents a gallon the last week to $3.70 a gallon, according to gasoline price website LincolnGasPrices.com. Sunday's prices were 11 cents a gallon higher than the same day a year ago and are almost 19 cents a gallon higher than a month ago.