Year billion cubic meters 1993 1.572 1994 1.479 1995 1.386 1996 1.348 1997 1.31 1998 1.2638333333 1999 1.2176666667 2000 1.1715 2001 1.13295 2002 1.0944 2003 1.0319 2004 0.9694 2005 0.9069 2006 0.7974 2007 0.6879 2008 0.6637 2009 0.6281 2010 0.6007 2011 0.5931 2012 0.6653 2013 0.6374 2014 0.5593 2015 0.5736 2016 0.5553 2017 0.5563 2018 0.5565 2019 0.5586 2020 0.555