Iraq was the world's 12th largest oil producer in 2009, and has the world's fifth largest proven petroleum reserves after Venezuela, Saudi Arabia, Canada, and Iran. Just a fraction of Iraq's known fields are in development, and Iraq may be one of the few places left where vast reserves, proven and unknown, have barely been exploited. Iraq's energy sector is heavily based upon oil, with approximately 94 percent of its energy needs met with petroleum. In addition, crude oil export revenues accounted for over two-thirds of GDP in 2009. Iraq's oil sector has suffered over the past several decades from sanctions and wars, and its oil infrastructure is in need of modernization and investment. As of June 30, 2010, the United States had allocated $2.05 billion to the Iraqi oil and gas sector to begin this modernization, but ended its direct involvement as of the first quarter of 2008.