Year	Tonnes
1971	3667
1972	7334
1973	11001
1974	14668
1975	22002
1976	33003
1977	47671
1978	69673
1979	99009
1980	143013
1981	190684
1982	238355
1983	289693
1984	348365
1985	414371
1986	495045
1987	575719
1988	671061
1989	795739
1990	968088
1991	1122102
1992	1353123
1993	1551141
1994	1749159
1995	1998515
1996	2288208
1997	2618238
1998	2918932
1999	3340637
2000	3791678
2001	4253720
2002	4847774
2003	5353820
2004	6021214
2005	6622602
2006	7381671
2007	8162742
2008	9006152
2009	9889899
2010	10824984
2011	11811407
2012	12922508
2013	14015274
2014	15350062