Year	metric tons
1960	650
1961	660
1962	670
1963	600
1964	680
1965	730
1966	750
1967	790
1968	740
1969	800
1970	870
1971	960
1972	1080
1973	1300
1974	1220
1975	1200
1976	1390
1977	1600
1978	2900
1979	3400
1980	3200
1981	3200
1982	3100
1983	3600
1984	4000
1985	4100
1986	4060
1987	4000
1988	4500
1989	4450
1990	3126
1991	3135
1992	3140
1993	3140
1994	3103
1995	2918
1996	2949
1997	3018
1998	2909
1999	3067
2000	2847
2001	2393
2002	2333
2003	2233
2004	2267
2005	2420
2006	2503
2007	2539
2008	2087
2009	2141
2010	2167
2011	2904.3
2012	3125.5
2013	3237
2014	3390.3
2015	3503.4
2016	3483.4
2017	3861.9
2018	3991.6
2019	4255.04
2020	4541.91
2021	4920.39
2022	4718.72