Year	metric tons
1960	400
1961	500
1962	500
1963	600
1964	600
1965	700
1966	800
1967	1000
1968	1000
1969	1000
1970	1500
1971	1500
1972	1500
1973	1500
1974	1500
1975	1500
1976	1500
1977	1503
1978	1505
1979	1505
1980	1720
1981	1720
1982	1777
1983	1777
1984	1777
1985	3564
1986	3864
1987	3766
1988	2973
1989	2266
1990	2367
1991	12552
1992	16740
1993	18168
1994	22310
1995	8082
1996	8808
1997	9781
1998	15807
1999	12589
2000	23460
2001	19471
2002	22926
2003	33753
2004	31972
2005	32361
2006	15442
2007	20873
2008	25445
2009	28606
2010	31526
2011	38142.06
2012	48420.62
2013	40972.1
2014	52496
2015	71567
2016	88690
2017	101417
2018	137920.65
2019	181769.51
2020	193747.86
2021	166333.97