Energy is the leading economic sector. Production of crude oil and natural gas condensate from the oil and gas basins of Kazakhstan amounted to  in 2012 up from  in 2003. Kazakhstan raised oil and gas condensate exports to 44.3 million tons in 2003, 13% higher than in 2002. Gas production in Kazakhstan in 2003, amounted to , up 22.7% compared to 2002, including natural gas production of . Kazakhstan holds about  of proven recoverable oil reserves and  of gas. Kazakhstan is the 19th largest oil-producing nation in the world. Kazakhstan's oil exports in 2003, were valued at more than $7 billion, representing 65% of overall exports and 24% of the GDP. Major oil and gas fields and recoverable oil reserves are Tengiz with ; Karachaganak with  and  of natural gas; and Kashagan with 7 to .