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	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	5
1992	5
1993	5
1994	5
1995	5
1996	5
1997	5
1998	5
1999	5
2000	5
2001	10
2002	10
2003	10
2004	10
2005	10
2006	18
2007	18
2008	18
2009	18
2010	18
2011	20
2012	20
2013	20
2014	20
2015	20
2016	20
2017	20
2018	20
2019	20
2020	15
2021	15
2022	18