Year metric tons 1960 31200 1961 30600 1962 35000 1963 35612 1964 37165 1965 41080 1966 43826 1967 65955 1968 66170 1969 78699 1970 104150 1971 126650 1972 139141 1973 149707 1974 163819 1975 143013 1976 193180 1977 183439 1978 211486 1979 151711 1980 184141 1981 161857 1982 191517 1983 194349 1984 195475.3 1985 215225.9 1986 239932.3 1987 209195.6 1988 225323.1 1989 185846.9 1990 179893.8 1991 162800.6 1992 100966.8 1993 84934.3 1994 77701.4 1995 80066.2 1996 84206.8 1997 76801.5 1998 58738.1 1999 60645.1 2000 68486 2001 54708 2002 32586 2003 34088 2004 32194 2005 28234 2006 27587 2007 29485 2008 28714 2009 28892 2010 23996 2011 24106 2012 22320 2013 22103 2014 25056 2015 25634 2016 23574 2017 21548 2018 22621 2019 18546.1 2020 20186.2 2021 18052.8 2022 14534.5