The same reason that cars, clothes, and everything else keep going up. Even with the recent slow economy in areas of this country for the most part we have more money to spend on the things we want than ever before. Even if we dont have the money Visa or Mastercard will be glad to help you out. As long as americans are will to accept increasing personal debt, prices for everything will continue to rise. Think about it, if no one was willing to to finance a new car for five years or a house for thirty years there is no way the prices would be as high as they are now because most people could not afford to buy them.
BruceP