Year	mmol per litre
1980	5.776
1981	5.761
1982	5.746
1983	5.73
1984	5.713
1985	5.695
1986	5.678
1987	5.662
1988	5.644
1989	5.624
1990	5.603
1991	5.577
1992	5.552
1993	5.528
1994	5.506
1995	5.484
1996	5.46
1997	5.437
1998	5.416
1999	5.396
2000	5.374
2001	5.351
2002	5.327
2003	5.303
2004	5.277
2005	5.256
2006	5.236
2007	5.221
2008	5.202