Year billion cubic meters 1995 0.01 1996 0.00995 1997 0.0099 1998 0.00985 1999 0.0098 2000 0.00975 2001 0.0097 2002 0.0094174444 2003 0.0093342222 2004 0.009251 2005 0.0095 2006 0.0093 2007 0.0091 2008 0.0089 2009 0.0087 2010 0.0085 2011 0.0083 2012 0.0081 2013 0.0079 2014 0.0079 2015 0.0079 2016 0.0079 2017 0.0079 2018 0.0079 2019 0.0079 2020 0.0079