Year	mmol per litre
1980	5.832
1981	5.803
1982	5.771
1983	5.74
1984	5.715
1985	5.687
1986	5.654
1987	5.622
1988	5.593
1989	5.56
1990	5.526
1991	5.498
1992	5.467
1993	5.438
1994	5.416
1995	5.389
1996	5.358
1997	5.329
1998	5.302
1999	5.273
2000	5.251
2001	5.223
2002	5.194
2003	5.166
2004	5.137
2005	5.107
2006	5.082
2007	5.059
2008	5.036