Year	mmol per litre
1980	5.855
1981	5.835
1982	5.815
1983	5.795
1984	5.778
1985	5.759
1986	5.736
1987	5.712
1988	5.69
1989	5.662
1990	5.634
1991	5.607
1992	5.579
1993	5.551
1994	5.526
1995	5.499
1996	5.47
1997	5.441
1998	5.414
1999	5.384
2000	5.359
2001	5.332
2002	5.304
2003	5.277
2004	5.25
2005	5.224
2006	5.203
2007	5.183
2008	5.165