Year	metric tons
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	50
1969	50
1970	50
1971	50
1972	50
1973	50
1974	50
1975	50
1976	50
1977	53
1978	44
1979	60
1980	70
1981	70
1982	80
1983	80
1984	82
1985	78
1986	82
1987	81
1988	90
1989	70
1990	65
1991	60
1992	60
1993	68
1994	60
1995	50
1996	50
1997	50
1998	50
1999	50
2000	50
2001	50
2002	60
2003	60
2004	60
2005	60
2006	60
2007	60
2008	60
2009	60
2010	60
2011	60
2012	60
2013	60
2014	65
2015	65
2016	65
2017	65
2018	65
2019	65
2020	60
2021	65
2022	65