Year	metric tons
1960	100
1961	100
1962	100
1963	100
1964	100
1965	100
1966	100
1967	100
1968	100
1969	100
1970	100
1971	100
1972	100
1973	100
1974	91
1975	131
1976	95
1977	184
1978	200
1979	162
1980	253
1981	315
1982	399
1983	290
1984	348
1985	433
1986	425
1987	320
1988	395
1989	340
1990	476
1991	514
1992	388
1993	388
1994	398
1995	266
1996	260
1997	271
1998	355
1999	324
2000	624
2001	673
2002	435
2003	456
2004	532
2005	280
2006	418
2007	326
2008	329
2009	462
2010	167.77
2011	120.49
2012	101.48
2013	108.68
2014	87.41
2015	71.62
2016	69.8
2017	152.42
2018	94.85
2019	90.2
2020	47.14
2021	25.69
2022	351.5