Year	metric tons
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	2
1970	10
1971	100
1972	500
1973	1000
1974	1800
1975	2300
1976	2746
1977	3000
1978	3238
1979	3443
1980	3622
1981	3774
1982	3899
1983	3997
1984	4476
1985	4441
1986	4564
1987	5250
1988	5000
1989	3000
1990	1600
1991	1750
1992	4750
1993	4000
1994	4100
1995	2600
1996	2500
1997	3400
1998	7500
1999	2183
2000	1745
2001	2000
2002	2000
2003	2000
2004	13947
2005	17941
2006	14867
2007	15810
2008	19246
2009	18732
2010	20320
2011	16290
2012	25040
2013	14060
2014	26625
2015	24803
2016	28835
2017	31814
2018	25737
2019	22269
2020	22704
2021	22694
2022	23000