Year	mmol per litre
1980	5.728
1981	5.71
1982	5.69
1983	5.672
1984	5.656
1985	5.641
1986	5.624
1987	5.605
1988	5.586
1989	5.566
1990	5.545
1991	5.523
1992	5.502
1993	5.482
1994	5.463
1995	5.442
1996	5.42
1997	5.398
1998	5.377
1999	5.357
2000	5.334
2001	5.31
2002	5.287
2003	5.264
2004	5.241
2005	5.219
2006	5.197
2007	5.173
2008	5.15