Year billion cubic meters 2000 9.5625 2001 9.54942 2002 9.53634 2003 9.52326 2004 9.51018 2005 9.4971 2006 9.4971 2007 9.4971 2008 9.4971 2009 9.4971 2010 9.4971 2011 9.4971 2012 9.4971 2013 9.4971 2014 9.4971 2015 9.4971 2016 9.4971 2017 9.4971 2018 9.4971 2019 9.4971 2020 9.4971