Year	metric tons
1960	100
1961	150
1962	150
1963	150
1964	150
1965	200
1966	200
1967	200
1968	200
1969	200
1970	150
1971	150
1972	150
1973	150
1974	150
1975	150
1976	150
1977	150
1978	150
1979	145
1980	143
1981	143
1982	98
1983	245
1984	345
1985	241
1986	311
1987	218
1988	227
1989	258
1990	175
1991	133
1992	153
1993	147
1994	178
1995	193
1996	249
1997	264
1998	255
1999	192
2000	336
2001	406
2002	296
2003	172
2004	169
2005	214
2006	227
2007	230
2008	184
2009	213
2010	153.24
2011	122.99
2012	132.53
2013	189.12
2014	188.14
2015	145.17000000000002
2016	140.84
2017	160.57999999999998
2018	156.29000000000002
2019	139.26999999999998
2020	143.37
2021	230.21