Year	Tonnes
1981	55.005
1982	66.006
1983	51.338
1984	51.338
1985	51.338
1986	58.672
1987	55.005
1988	66.006
1989	66.006
1990	106.343
1991	106.343
1992	110.01
1993	113.677
1994	121.011
1995	128.345
1996	132.012
1997	143.013
1998	150.347
1999	161.348
2000	172.349
2001	176.016
2002	198.018
2003	198.018
2004	212.686
2005	198.018
2006	201.685
2007	216.353
2008	216.353
2009	223.687
2010	220.02
2011	231.021
2012	220.02
2013	223.687
2014	231.021