Year	mmol per litre
1980	5.863
1981	5.87
1982	5.878
1983	5.882
1984	5.885
1985	5.884
1986	5.879
1987	5.871
1988	5.863
1989	5.853
1990	5.84
1991	5.82
1992	5.798
1993	5.773
1994	5.739
1995	5.705
1996	5.667
1997	5.626
1998	5.585
1999	5.542
2000	5.497
2001	5.451
2002	5.401
2003	5.349
2004	5.3
2005	5.251
2006	5.21
2007	5.165
2008	5.125