Year	billion cubic meters
1961	58
1962	58
1963	58
1964	58
1965	58
1966	58
1967	58
1968	58
1969	58
1970	58
1971	58
1972	58
1973	58
1974	58
1975	58
1976	58
1977	58
1978	58
1979	58
1980	58
1981	58
1982	58
1983	58
1984	58
1985	58
1986	58
1987	58
1988	58
1989	58
1990	58
1991	58
1992	58
1993	58
1994	58
1995	58
1996	58
1997	58
1998	58
1999	58
2000	58
2001	58
2002	58
2003	58
2004	58
2005	58
2006	58
2007	58
2008	58
2009	58
2010	58
2011	58
2012	58
2013	58
2014	58
2015	58
2016	58
2017	58
2018	58
2019	58
2020	58