Year	billion cubic meters
1961	7.1
1962	7.1
1963	7.1
1964	7.1
1965	7.1
1966	7.1
1967	7.1
1968	7.1
1969	7.1
1970	7.1
1971	7.1
1972	7.1
1973	7.1
1974	7.1
1975	7.1
1976	7.1
1977	7.1
1978	7.1
1979	7.1
1980	7.1
1981	7.1
1982	7.1
1983	7.1
1984	7.1
1985	7.1
1986	7.1
1987	7.1
1988	7.1
1989	7.1
1990	7.1
1991	7.1
1992	7.1
1993	7.1
1994	7.1
1995	7.1
1996	7.1
1997	7.1
1998	7.1
1999	7.1
2000	7.1
2001	7.1
2002	7.1
2003	7.1
2004	7.1
2005	7.1
2006	7.1
2007	7.1
2008	7.1
2009	7.1
2010	7.1
2011	7.1
2012	7.1
2013	7.1
2014	7.1
2015	7.1
2016	7.1
2017	7.1
2018	7.1
2019	7.1
2020	7.1