Year	metric tons
1960	2000
1961	2000
1962	2000
1963	2500
1964	2500
1965	3000
1966	4000
1967	5000
1968	5000
1969	6000
1970	7000
1971	8000
1972	8000
1973	10000
1974	11883
1975	8044
1976	10465
1977	13000
1978	13000
1979	13000
1980	13000
1981	13000
1982	13000
1983	13000
1984	13000
1985	13000
1986	13000
1987	13000
1988	13000
1989	13000
1990	13000
1991	13500
1992	13000
1993	13250
1994	13500
1995	13750
1996	14000
1997	14250
1998	14500
1999	15000
2000	15000
2001	17000
2002	19000
2003	21000
2004	23000
2005	25000
2006	27000
2007	29000
2008	31000
2009	33000
2010	35000
2011	35000
2012	32000
2013	30000
2014	29000
2015	28000
2016	29000
2017	29000
2018	29000
2019	29000
2020	27500
2021	28000
2022	29000