Year billion cubic meters 1961 26.9 1962 26.9 1963 26.9 1964 26.9 1965 26.9 1966 26.9 1967 26.9 1968 26.9 1969 26.9 1970 26.9 1971 26.9 1972 26.9 1973 26.9 1974 26.9 1975 26.9 1976 26.9 1977 26.9 1978 26.9 1979 26.9 1980 26.9 1981 26.9 1982 26.9 1983 26.9 1984 26.9 1985 26.9 1986 26.9 1987 26.9 1988 26.9 1989 26.9 1990 26.9 1991 26.9 1992 26.9 1993 26.9 1994 26.9 1995 26.9 1996 26.9 1997 26.9 1998 26.9 1999 26.9 2000 26.9 2001 26.9 2002 26.9 2003 26.9 2004 26.9 2005 26.9 2006 26.9 2007 26.9 2008 26.9 2009 26.9 2010 26.9 2011 26.9 2012 26.9 2013 26.9 2014 26.9 2015 26.9 2016 26.9 2017 26.9 2018 26.9 2019 26.9 2020 26.9