Year	metric tons
1960	200
1961	300
1962	300
1963	300
1964	300
1965	300
1966	300
1967	400
1968	400
1969	460
1970	460
1971	560
1972	560
1973	560
1974	560
1975	660
1976	770
1977	770
1978	770
1979	770
1980	870
1981	870
1982	870
1983	970
1984	970
1985	970
1986	970
1987	1170
1988	1170
1989	1170
1990	1400
1991	1400
1992	1500
1993	1500
1994	1600
1995	1600
1996	1600
1997	1550
1998	1500
1999	1500
2000	1300
2001	1250
2002	1350
2003	1350
2004	1450
2005	1450
2006	1450
2007	2050
2008	2050
2009	2650
2010	3250
2011	4000
2012	4780
2013	5560
2014	6360
2015	7200
2016	8050
2017	9000
2018	10000
2019	10729
2020	11444
2021	12907
2022	13150