Year billion cubic meters 1986 42.2 1987 42.7786 1988 43.3572 1989 43.9358 1990 44.5117 1991 45.091 1992 44.515 1993 43.939 1994 43.363 1995 42.787 1996 42.211 1997 42.1297545455 1998 42.0485090909 1999 41.9672636364 2000 41.8860181818 2001 41.8047727273 2002 41.7235272727 2003 41.6422818182 2004 41.5610363636 2005 41.4797909091 2006 41.3985454545 2007 41.3173 2008 40.0573 2009 38.7973 2010 37.19865 2011 35.6 2012 36.44 2013 37.28 2014 36.505 2015 35.73 2016 35.9915 2017 36.253 2018 36.253 2019 36.253 2020 36.253