From the Energy Information Administration: "Natural gas has been an important exception to the trend of rising prices for energy sources used by manufacturers. Production of natural gas in the United States increased rapidly beginning in 2007 as a result of resources found in shale formations. That increase in supply has in turn lowered the price of natural gas to manufacturers as well as other consumers. *** The 36% decrease in the average natural gas price paid by manufacturers between 2006 and 2010, from $7.59 to $4.83 per million Btu, was large enough that the total cost of energy from all sources fell by 11% between 2006 and 2010, from $9.19 to $8.22 per million Btu (in 2005 dollars), according to data from the 2010 Manufacturing Energy Consumption Survey (MECS). Since that survey was conducted, natural gas prices have fallen further."