Year	mmol per litre
1980	5.915
1981	5.898
1982	5.878
1983	5.86
1984	5.842
1985	5.832
1986	5.821
1987	5.811
1988	5.805
1989	5.798
1990	5.789
1991	5.775
1992	5.764
1993	5.749
1994	5.737
1995	5.728
1996	5.716
1997	5.7
1998	5.685
1999	5.668
2000	5.652
2001	5.638
2002	5.621
2003	5.6
2004	5.583
2005	5.567
2006	5.551
2007	5.539
2008	5.522