Year	billion cubic meters
1980	443.7
1981	452.0825
1982	460.465
1983	468.8475
1984	477.23
1985	481.06
1986	484.848
1987	488.636
1988	492.424
1989	496.212
1990	500
1991	508.4666666667
1992	516.9333333333
1993	525.4
1994	529.0428571429
1995	532.6857142857
1996	536.3285714286
1997	539.9714285714
1998	543.6142857143
1999	547.2571428571
2000	550.9
2001	551.54
2002	552.18
2003	552.82
2004	553.46
2005	554.1
2006	568
2007	568.7
2008	576.1
2009	583.2
2010	586.83
2011	595
2012	598.8
2013	602.8
2014	593.4
2015	591.8
2016	604.02
2017	596.22
2018	592.91
2019	602.12
2020	568.48