Year billion cubic meters 1995 4.3472 1996 4.084 1997 3.8208 1998 3.5576 1999 3.2944 2000 3.0312 2001 2.768 2002 2.6661 2003 2.5642 2004 2.4623 2005 2.3604 2006 2.3122 2007 2.264 2008 1.8546 2009 1.4452 2010 1.0358 2011 0.6264 2012 0.5368 2013 0.4472 2014 0.3576 2015 0.3818 2016 0.3079 2017 0.259 2018 0.25439 2019 0.25439 2020 0.25439