U.S. consumers paid $38 billion more for gasoline in the first 6 months of 2006 than they paid in the same period of 2005, and $57 billion more than they paid in the same period of 2004, in large part because of rising oil prices, which reached a 24-year high in 2006 when adjusted for inflation. Oil is a global commodity, and its price is determined mainly by the balance between world demand and supply.