Year	billion cubic meters
1961	337
1962	337
1963	337
1964	337
1965	337
1966	337
1967	337
1968	337
1969	337
1970	337
1971	337
1972	337
1973	337
1974	337
1975	337
1976	337
1977	337
1978	337
1979	337
1980	337
1981	337
1982	337
1983	337
1984	337
1985	337
1986	337
1987	337
1988	337
1989	337
1990	337
1991	337
1992	337
1993	337
1994	337
1995	337
1996	337
1997	337
1998	337
1999	337
2000	337
2001	337
2002	337
2003	337
2004	337
2005	337
2006	337
2007	337
2008	337
2009	337
2010	337
2011	337
2012	337
2013	337
2014	337
2015	337
2016	337
2017	337
2018	337
2019	337
2020	337