Year	metric tons
1961	550
1962	550
1963	550
1964	550
1965	550
1966	540
1967	540
1968	540
1969	530
1970	530
1971	500
1972	450
1973	385
1974	426
1975	439
1976	492
1977	571
1978	663
1979	550
1980	447
1981	470
1982	423
1983	393
1984	393
1985	390
1986	245
1987	250
1988	252
1989	256
1990	258
1991	295
1992	337
1993	386
1994	347
1995	354
1996	330
1997	300
1998	289.13
1999	275.95
2000	305.16
2001	307.08
2002	317.12
2003	318.33
2004	315.18
2005	315
2006	300
2007	320
2008	329.4
2009	335.76
2010	342.5
2011	350.51
2012	360
2013	400
2014	410.56
2015	354.12
2016	388.23
2017	385.82
2018	385.87
2019	379.39
2020	382.34
2021	384.13
2022	385.91