Year	Kg per Square Metre
1980	24.67
1981	24.82
1982	24.98
1983	25.14
1984	25.3
1985	25.46
1986	25.63
1987	25.81
1988	26
1989	26.2
1990	26.39
1991	26.59
1992	26.78
1993	26.96
1994	27.14
1995	27.33
1996	27.49
1997	27.64
1998	27.78
1999	27.93
2000	28.08
2001	28.24
2002	28.4
2003	28.56
2004	28.72
2005	28.89
2006	29.05
2007	29.21
2008	29.37