Year	metric tons
1961	110
1962	110
1963	117
1964	135
1965	80
1966	5
1967	10
1968	14
1969	31
1970	23
1971	25
1972	30
1973	30
1974	30
1975	30
1976	30
1977	30
1978	30
1979	30
1980	30
1981	30
1982	30
1983	11
1984	21
1985	17
1986	20
1987	20
1988	20
1989	20
1990	21
1991	16
1992	16
1993	17
1994	18
1995	19
1996	21
1997	22
1998	24
1999	25
2000	27
2001	28
2002	30
2003	30
2004	31
2005	32
2006	32
2007	35
2008	38
2009	41
2010	43
2011	46
2012	50
2013	50
2014	52
2015	54
2016	50
2017	51