Year	metric tons
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	2
1985	2
1986	21
1987	25
1988	24
1989	25
1990	30
1991	50
1992	50
1993	50
1994	50
1995	50
1996	50
1997	50
1998	50
1999	50
2000	50
2001	50
2002	50
2003	50
2004	50
2005	50
2006	50
2007	50
2008	50
2009	50
2010	17.3
2011	61.7
2012	160.4
2013	205
2014	225
2015	366
2016	380
2017	440
2018	445
2019	495
2020	490
2021	540
2022	540