Year	billion cubic meters
1975	0.451
1976	0.4678
1977	0.4846
1978	0.5014
1979	0.5182
1980	0.535
1981	0.5518
1982	0.5686
1983	0.5854
1984	0.6022
1985	0.619
1986	0.6716
1987	0.7242
1988	0.7768
1989	0.8294
1990	0.835
1991	0.8855714286
1992	0.9361428571
1993	0.9128392857
1994	0.8908857143
1995	0.8689321429
1996	0.8469785714
1997	0.825025
1998	0.8032
1999	0.774375
2000	0.74555
2001	0.6981071429
2002	0.7386642857
2003	0.7432214286
2004	0.8027785714
2005	0.8662
2006	0.917
2007	0.932
2008	0.928
2009	0.863
2010	0.893
2011	0.796
2012	0.849
2013	0.901
2014	0.9698
2015	0.8682
2016	0.9036
2017	0.9069
2018	0.923
2019	0.94184
2020	0.94184