Year billion cubic meters 2005 0.01 2006 0.0104555556 2007 0.0109111111 2008 0.0113666667 2009 0.0118222222 2010 0.0122777778 2011 0.0127333333 2012 0.0131888889 2013 0.0136444444 2014 0.0141 2015 0.0141 2016 0.0141 2017 0.0141 2018 0.0141 2019 0.0141 2020 0.0141