Year	mmol per litre
1980	4.863
1981	4.866
1982	4.864
1983	4.856
1984	4.851
1985	4.846
1986	4.844
1987	4.842
1988	4.839
1989	4.84
1990	4.85
1991	4.86
1992	4.872
1993	4.884
1994	4.895
1995	4.909
1996	4.923
1997	4.935
1998	4.946
1999	4.96
2000	4.971
2001	4.983
2002	4.992
2003	5.002
2004	5.009
2005	5.015
2006	5.022
2007	5.024
2008	5.026