Year	billion cubic meters
1961	9.5
1962	9.5
1963	9.5
1964	9.5
1965	9.5
1966	9.5
1967	9.5
1968	9.5
1969	9.5
1970	9.5
1971	9.5
1972	9.5
1973	9.5
1974	9.5
1975	9.5
1976	9.5
1977	9.5
1978	9.5
1979	9.5
1980	9.5
1981	9.5
1982	9.5
1983	9.5
1984	9.5
1985	9.5
1986	9.5
1987	9.5
1988	9.5
1989	9.5
1990	9.5
1991	9.5
1992	9.5
1993	9.5
1994	9.5
1995	9.5
1996	9.5
1997	9.5
1998	9.5
1999	9.5
2000	9.5
2001	9.5
2002	9.5
2003	9.5
2004	9.5
2005	9.5
2006	9.5
2007	9.5
2008	9.5
2009	9.5
2010	9.5
2011	9.5
2012	9.5
2013	9.5
2014	9.5
2015	9.5
2016	9.5
2017	9.5
2018	9.5
2019	9.5
2020	9.5