Year	mmol per litre
1980	5.644
1981	5.633
1982	5.621
1983	5.609
1984	5.596
1985	5.585
1986	5.571
1987	5.56
1988	5.551
1989	5.545
1990	5.537
1991	5.526
1992	5.503
1993	5.472
1994	5.438
1995	5.407
1996	5.37
1997	5.335
1998	5.304
1999	5.277
2000	5.255
2001	5.234
2002	5.22
2003	5.207
2004	5.198
2005	5.192
2006	5.192
2007	5.19
2008	5.183