Year	mmol per litre
1980	5.647
1981	5.628
1982	5.605
1983	5.585
1984	5.565
1985	5.546
1986	5.527
1987	5.507
1988	5.492
1989	5.48
1990	5.467
1991	5.45
1992	5.434
1993	5.417
1994	5.402
1995	5.387
1996	5.369
1997	5.348
1998	5.331
1999	5.314
2000	5.297
2001	5.281
2002	5.263
2003	5.244
2004	5.226
2005	5.205
2006	5.185
2007	5.163
2008	5.141