Year	metric tons
1960	4500
1961	4500
1962	4500
1963	4500
1964	4500
1965	4600
1966	4600
1967	4700
1968	5000
1969	5000
1970	5600
1971	5700
1972	5800
1973	5900
1974	5980
1975	10350
1976	8268
1977	9830
1978	8384
1979	10984
1980	14330
1981	9823
1982	9030
1983	11495
1984	19939
1985	16767
1986	18655
1987	19996
1988	20327
1989	21546
1990	22695
1991	23800
1992	25750
1993	27750
1994	29850
1995	32400
1996	30200
1997	28000
1998	25800
1999	28650
2000	24150
2001	31900
2002	29000
2003	30000
2004	30000
2005	25000
2006	30000
2007	30000
2008	30000
2009	30000
2010	30000
2011	30000
2012	30000
2013	30000
2014	30000
2015	30000
2016	30000
2017	30000
2018	30000
2019	30000
2020	30000
2021	30000
2022	30000