Year	billion cubic meters
1961	580
1962	580
1963	580
1964	580
1965	580
1966	580
1967	580
1968	580
1969	580
1970	580
1971	580
1972	580
1973	580
1974	580
1975	580
1976	580
1977	580
1978	580
1979	580
1980	580
1981	580
1982	580
1983	580
1984	580
1985	580
1986	580
1987	580
1988	580
1989	580
1990	580
1991	580
1992	580
1993	580
1994	580
1995	580
1996	580
1997	580
1998	580
1999	580
2000	580
2001	580
2002	580
2003	580
2004	580
2005	580
2006	580
2007	580
2008	580
2009	580
2010	580
2011	580
2012	580
2013	580
2014	580
2015	580
2016	580
2017	580
2018	580
2019	580
2020	580