Year	billion cubic meters
1961	53.6
1962	53.6
1963	53.6
1964	53.6
1965	53.6
1966	53.6
1967	53.6
1968	53.6
1969	53.6
1970	53.6
1971	53.6
1972	53.6
1973	53.6
1974	53.6
1975	53.6
1976	53.6
1977	53.6
1978	53.6
1979	53.6
1980	53.6
1981	53.6
1982	53.6
1983	53.6
1984	53.6
1985	53.6
1986	53.6
1987	53.6
1988	53.6
1989	53.6
1990	53.6
1991	53.6
1992	53.6
1993	53.6
1994	53.6
1995	53.6
1996	53.6
1997	53.6
1998	53.6
1999	53.6
2000	53.6
2001	53.6
2002	53.6
2003	53.6
2004	53.6
2005	53.6
2006	53.6
2007	53.6
2008	53.6
2009	53.6
2010	53.6
2011	53.6
2012	53.6
2013	53.6
2014	53.6
2015	53.6
2016	53.6
2017	53.6
2018	53.6
2019	53.6
2020	53.6