The average price of a gallon of regular gasoline nationwide had a slight increase in the past week.  Gas was at $1.71 per gallon, up from $1.70, while it was at $2.26 per gallon one year ago.  There was a significant increase in Illinois for the past week, as it went up from $1.53 per gallon of regular to $1.66.  There was a slight change in Nashville, as it dropped a penny from $1.57 per gallon of regular gas to $1.56 for the past week.