Year	metric tons
1960	100
1961	100
1962	100
1963	150
1964	150
1965	150
1966	150
1967	150
1968	150
1969	150
1970	150
1971	150
1972	150
1973	150
1974	150
1975	150
1976	150
1977	150
1978	150
1979	150
1980	150
1981	145
1982	140
1983	135
1984	130
1985	125
1986	120
1987	115
1988	125
1989	117
1990	131
1991	130
1992	125
1993	115
1994	110
1995	105
1996	100
1997	95
1998	90
1999	85
2000	80
2001	75
2002	70
2003	65
2004	70
2005	65
2006	60
2007	55
2008	56
2009	54
2010	52
2011	79
2012	80.34
2013	72.8
2014	144
2015	156
2016	197
2017	238
2018	223.62
2019	209.77
2020	181.5
2021	194.1
2022	199.88