Year	mmol per litre
1980	5.975
1981	5.964
1982	5.952
1983	5.939
1984	5.926
1985	5.91
1986	5.892
1987	5.874
1988	5.858
1989	5.841
1990	5.823
1991	5.8
1992	5.776
1993	5.751
1994	5.716
1995	5.681
1996	5.643
1997	5.601
1998	5.559
1999	5.518
2000	5.474
2001	5.429
2002	5.38
2003	5.329
2004	5.282
2005	5.236
2006	5.195
2007	5.151
2008	5.111