Year billion cubic meters 1996 0.0166 1997 0.0166 1998 0.0166 1999 0.0166 2000 0.0166 2001 0.0166 2002 0.0166 2003 0.0166 2004 0.0166 2005 0.0171666667 2006 0.0177333333 2007 0.0183 2008 0.0188666667 2009 0.0194333333 2010 0.02 2011 0.02 2012 0.02 2013 0.02 2014 0.02 2015 0.02 2016 0.02 2017 0.02 2018 0.02 2019 0.02 2020 0.02