Year	Kg per Square Metre
1980	22.47
1981	22.59
1982	22.71
1983	22.86
1984	23
1985	23.13
1986	23.27
1987	23.42
1988	23.56
1989	23.71
1990	23.85
1991	23.98
1992	24.11
1993	24.24
1994	24.35
1995	24.47
1996	24.6
1997	24.72
1998	24.85
1999	25
2000	25.15
2001	25.29
2002	25.44
2003	25.57
2004	25.71
2005	25.85
2006	25.99
2007	26.13
2008	26.26