Year	mmol per litre
1980	5.774
1981	5.758
1982	5.74
1983	5.721
1984	5.701
1985	5.681
1986	5.66
1987	5.636
1988	5.613
1989	5.589
1990	5.563
1991	5.532
1992	5.496
1993	5.461
1994	5.421
1995	5.379
1996	5.334
1997	5.293
1998	5.253
1999	5.221
2000	5.19
2001	5.165
2002	5.144
2003	5.129
2004	5.118
2005	5.109
2006	5.101
2007	5.096
2008	5.091