Year	billion cubic meters
1970	3.3
1971	3.35
1972	3.4
1973	3.45
1974	3.5
1975	3.55
1976	3.58
1977	3.61
1978	3.64
1979	3.67
1980	3.7
1981	3.76
1982	3.82
1983	3.88
1984	3.94
1985	4
1986	3.6654
1987	3.3308
1988	2.9962
1989	2.6616
1990	2.327
1991	2.3788
1992	2.4306
1993	2.4824
1994	2.5342
1995	2.586
1996	2.521425
1997	2.45685
1998	2.392275
1999	2.3277
2000	2.9355571429
2001	3.5434142857
2002	4.1512714286
2003	4.7539535714
2004	5.3566357143
2005	5.9593178571
2006	6.562
2007	6.1358
2008	5.7096
2009	5.2834
2010	4.8572
2011	4.431
2012	4.0048
2013	3.5786
2014	3.1524
2015	2.7262
2016	2.3
2017	2.3
2018	2.8
2019	3
2020	3