This is a combination of data from the EIA Annual Energy Outlook 2009 and 2010. The price data for 2009 were given in 2007 $ and were scaled to account for inflation. The demand curve for 2009 shows an inflection at years past 2025, which is not reflected in the AEO 2010 data. The term "quad" refers to quadrillion (1015) BTU). Each quadrillion BTU of natural gas is equivalent to approximately 1000 billion standard cubic feet of gas.