Year	metric tons
1960	6000
1961	6500
1962	7000
1963	7000
1964	7000
1965	8000
1966	8000
1967	8000
1968	9000
1969	9000
1970	10000
1971	10000
1972	10000
1973	12000
1974	12000
1975	14900
1976	14820
1977	14010
1978	17800
1979	21000
1980	19800
1981	20146
1982	20605
1983	19449
1984	21002
1985	20955
1986	20226
1987	22188
1988	22093
1989	20502
1990	20002
1991	22003
1992	24005
1993	31797
1994	31043
1995	40476
1996	46175
1997	44250
1998	53912
1999	51813
2000	48384
2001	42973
2002	41653
2003	45559
2004	46152
2005	43941
2006	41647
2007	37938
2008	31450
2009	29715
2010	32822
2011	36652
2012	36548
2013	36646
2014	36900
2015	33045
2016	31050
2017	29050
2018	29062
2019	29062
2020	28952
2021	29912
2022	31097