Year	billion cubic meters
1961	111.2
1962	111.2
1963	111.2
1964	111.2
1965	111.2
1966	111.2
1967	111.2
1968	111.2
1969	111.2
1970	111.2
1971	111.2
1972	111.2
1973	111.2
1974	111.2
1975	111.2
1976	111.2
1977	111.2
1978	111.2
1979	111.2
1980	111.2
1981	111.2
1982	111.2
1983	111.2
1984	111.2
1985	111.2
1986	111.2
1987	111.2
1988	111.2
1989	111.2
1990	111.2
1991	111.2
1992	111.2
1993	111.2
1994	111.2
1995	111.2
1996	111.2
1997	111.2
1998	111.2
1999	111.2
2000	111.2
2001	111.2
2002	111.2
2003	111.2
2004	111.2
2005	111.2
2006	111.2
2007	111.2
2008	111.2
2009	111.2
2010	111.2
2011	111.2
2012	111.2
2013	111.2
2014	111.2
2015	111.2
2016	111.2
2017	111.2
2018	111.2
2019	111.2
2020	111.2