Year	mm Hg
1980	132.2
1981	132
1982	131.9
1983	131.8
1984	131.7
1985	131.5
1986	131.4
1987	131.3
1988	131.2
1989	131.1
1990	131
1991	130.9
1992	130.6
1993	130.3
1994	130
1995	129.6
1996	129.3
1997	129
1998	128.8
1999	128.6
2000	128.5
2001	128.5
2002	128.5
2003	128.5
2004	128.4
2005	128.5
2006	128.5
2007	128.6
2008	128.6