Despite U.S. petroleum reserves being at an eight-year high, the price of oil rose dramatically beginning in 2006. While demand rose, supply kept pace. Yet, prices still skyrocketed. This means that the laws of supply and demand no longer applied in the oil markets. Instead, an artificial market developed.
Artificial markets are volatile; they're difficult to predict and can turn on a dime. As a result of the artificial oil market, the average price per barrel of crude oil increased from $31.61 in July 2004 to $137.11 in July 2008 [source: DOE]. The average cost for a gallon of regular unleaded gas in the United States grew from $1.93 to $4.09 over the same period.