Year	Kg per Square Metre
1980	23.98
1981	24.09
1982	24.21
1983	24.32
1984	24.43
1985	24.54
1986	24.63
1987	24.75
1988	24.87
1989	24.99
1990	25.11
1991	25.25
1992	25.4
1993	25.56
1994	25.72
1995	25.88
1996	26.03
1997	26.19
1998	26.34
1999	26.5
2000	26.65
2001	26.8
2002	26.95
2003	27.09
2004	27.24
2005	27.39
2006	27.54
2007	27.69
2008	27.84