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	1
1980	2
1981	2
1982	3
1983	4
1984	7
1985	9
1986	14
1987	18
1988	20
1989	20
1990	20
1991	20
1992	20
1993	15
1994	25
1995	25
1996	30
1997	30
1998	30
1999	30
2000	30
2001	30
2002	30
2003	30
2004	30
2005	30
2006	30
2007	50
2008	50
2009	75
2010	75
2011	75
2012	75
2013	75
2014	75
2015	85
2016	85
2017	85
2018	100
2019	100
2020	115
2021	125
2022	145