Year	metric tons
1960	2100
1961	1900
1962	2000
1963	2200
1964	2000
1965	2300
1966	2500
1967	1800
1968	2500
1969	3000
1970	2300
1971	2000
1972	1800
1973	2400
1974	3100
1975	2400
1976	1700
1977	1600
1978	1700
1979	1650
1980	1700
1981	1500
1982	1400
1983	1300
1984	1200
1985	1400
1986	1500
1987	1713
1988	1713
1989	1713
1990	1430
1991	1732
1992	1731
1993	2032
1994	2237
1995	4085
1996	4135
1997	3655
1998	3520
1999	3560
2000	3666
2001	3670
2002	3970
2003	3898
2004	3866
2005	3798
2006	3811
2007	3700
2008	3600
2009	3500
2010	3400
2011	3300
2012	3200
2013	3100
2014	2998
2015	3638
2016	4291
2017	3617
2018	2796
2019	2619.8
2020	2455
2021	2580
2022	2620