Year billion cubic meters 1970 2 1971 2.1 1972 2.2 1973 2.3 1974 2.4 1975 2.5 1976 2.6 1977 2.7 1978 2.8 1979 2.9 1980 3 1981 3.1 1982 3.2 1983 3.3 1984 3.4 1985 3.5 1986 3.7 1987 3.9 1988 4.1 1989 4.3 1990 4.436 1991 4.5557090909 1992 4.6754181818 1993 4.7951272727 1994 4.9148363636 1995 5.0345454545 1996 5.1542545455 1997 5.2739636364 1998 5.3936727273 1999 5.5133818182 2000 5.6330909091 2001 5.8071666667 2002 6.0436060606 2003 6.2202454545 2004 6.3968848485 2005 6.5735242424 2006 6.7501636364 2007 6.9268030303 2008 7.1034424242 2009 7.2800818182 2010 7.4567212121 2011 7.6333606061 2012 7.8 2013 8.1846666667 2014 8.5693333333 2015 8.954 2016 9.23 2017 9.802 2018 9.802 2019 9.802 2020 9.802