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	21000
1985	20953
1986	20223
1987	22185
1988	22091
1989	20500
1990	20000
1991	22000
1992	24000
1993	31789
1994	31015
1995	40437
1996	46113
1997	44193
1998	53754
1999	51255
2000	47826
2001	42871
2002	41570
2003	45479
2004	46072
2005	43863
2006	41521
2007	37814
2008	31326
2009	29589
2010	32692
2011	36522
2012	36500
2013	36600
2014	36855
2015	33000
2016	31000
2017	29000
2018	29000
2019	29000
2020	28880
2021	29840
2022	31010