Year	billion cubic meters
1975	2.598
1976	2.5962
1977	2.5944
1978	2.5926
1979	2.5908
1980	2.589
1981	2.6004
1982	2.6118
1983	2.6232
1984	2.6346
1985	2.646
1986	2.653
1987	2.66
1988	2.667
1989	2.674
1990	2.681
1991	2.688
1992	2.695
1993	2.66762
1994	2.64024
1995	2.61286
1996	2.58548
1997	2.5581
1998	2.55008
1999	2.54206
2000	2.53404
2001	2.52602
2002	2.518
2003	2.46665
2004	2.4153
2005	2.36395
2006	2.3126
2007	2.26125
2008	2.2099
2009	2.15855
2010	2.1072
2011	2.05585
2012	2
2013	1.72
2014	1.704
2015	1.705917
2016	1.704
2017	1.704
2018	1.704
2019	1.704
2020	1.704