Year	billion cubic meters
1980	30.964
1981	31.7478
1982	32.5316
1983	33.3154
1984	34.0992
1985	34.883
1986	35.4426
1987	36.0022
1988	36.5618
1989	37.1214
1990	37.681
1991	38.45
1992	39.219
1993	37.4414
1994	35.6638
1995	33.8862
1996	32.1086
1997	30.331
1998	31.1203333333
1999	31.9096666667
2000	32.699
2001	32.5265
2002	32.354
2003	32.7186666667
2004	33.0833333333
2005	33.448
2006	32.22
2007	30.992
2008	28.66
2009	28.4703
2010	28.578
2011	30.146
2012	28.063
2013	27.157
2014	27.297
2015	28.116
2016	26.436
2017	26.946
2018	26.92292431
2019	26.27207965
2020	26.27207965