Year billion cubic meters 1990 20.57 1991 21.2657142857 1992 21.9614285714 1993 22.6571428571 1994 23.3528571429 1995 24.0485714286 1996 24.7442857143 1997 25.44 1998 26.1856 1999 26.9312 2000 27.6768 2001 28.4224 2002 29.168 2003 29.1776666667 2004 29.1873333333 2005 29.197 2006 29.197 2007 29.197 2008 29.197 2009 29.197 2010 29.197 2011 29.197 2012 29.197 2013 29.197 2014 29.197 2015 29.197 2016 29.197 2017 29.197 2018 29.197 2019 29.197 2020 29.197