Year	mmol per litre
1980	4.878
1981	4.883
1982	4.885
1983	4.888
1984	4.891
1985	4.892
1986	4.892
1987	4.893
1988	4.897
1989	4.902
1990	4.91
1991	4.921
1992	4.933
1993	4.949
1994	4.966
1995	4.984
1996	5.002
1997	5.02
1998	5.031
1999	5.039
2000	5.049
2001	5.058
2002	5.067
2003	5.078
2004	5.087
2005	5.094
2006	5.102
2007	5.109
2008	5.118