Year	mmol per litre
1980	5.763
1981	5.742
1982	5.722
1983	5.702
1984	5.68
1985	5.658
1986	5.639
1987	5.622
1988	5.605
1989	5.588
1990	5.57
1991	5.547
1992	5.524
1993	5.504
1994	5.487
1995	5.467
1996	5.445
1997	5.422
1998	5.402
1999	5.381
2000	5.357
2001	5.329
2002	5.301
2003	5.271
2004	5.238
2005	5.209
2006	5.181
2007	5.156
2008	5.128