Year	billion cubic meters
1961	100.3
1962	100.3
1963	100.3
1964	100.3
1965	100.3
1966	100.3
1967	100.3
1968	100.3
1969	100.3
1970	100.3
1971	100.3
1972	100.3
1973	100.3
1974	100.3
1975	100.3
1976	100.3
1977	100.3
1978	100.3
1979	100.3
1980	100.3
1981	100.3
1982	100.3
1983	100.3
1984	100.3
1985	100.3
1986	100.3
1987	100.3
1988	100.3
1989	100.3
1990	100.3
1991	100.3
1992	100.3
1993	100.3
1994	100.3
1995	100.3
1996	100.3
1997	100.3
1998	100.3
1999	100.3
2000	100.3
2001	100.3
2002	100.3
2003	100.3
2004	100.3
2005	100.3
2006	100.3
2007	100.3
2008	100.3
2009	100.3
2010	100.3
2011	100.3
2012	100.3
2013	100.3
2014	100.3
2015	100.3
2016	100.3
2017	100.3
2018	100.3
2019	100.3
2020	100.3