Gas prices went up on a national average this past week, but rose a little more in Illinois.  The national average price for a gallon of regular gasoline is at $3.61, up a nickel from the week before.  The average a year ago was $3.57, but the average for a gallon of regular gas in Illinois is now at $3.84, up 6 cents from the week before and one of the highest amounts in quite a while.  March and April are the annual seasonal increase months heading into the summer.