Year	mmol per litre
1980	6.082
1981	6.055
1982	6.029
1983	6.005
1984	5.982
1985	5.963
1986	5.943
1987	5.924
1988	5.9
1989	5.876
1990	5.851
1991	5.827
1992	5.797
1993	5.768
1994	5.739
1995	5.71
1996	5.677
1997	5.647
1998	5.626
1999	5.604
2000	5.579
2001	5.556
2002	5.532
2003	5.505
2004	5.482
2005	5.459
2006	5.437
2007	5.416
2008	5.396