Year	mmol per litre
1980	4.877
1981	4.865
1982	4.85
1983	4.84
1984	4.825
1985	4.804
1986	4.784
1987	4.761
1988	4.741
1989	4.719
1990	4.7
1991	4.683
1992	4.665
1993	4.65
1994	4.641
1995	4.631
1996	4.618
1997	4.608
1998	4.595
1999	4.579
2000	4.565
2001	4.551
2002	4.539
2003	4.525
2004	4.51
2005	4.497
2006	4.485
2007	4.474
2008	4.463