Year	mm Hg
1980	129.7
1981	129.6
1982	129.5
1983	129.4
1984	129.4
1985	129.3
1986	129.3
1987	129.3
1988	129.3
1989	129.3
1990	129.3
1991	129.3
1992	129.2
1993	129.1
1994	129
1995	128.8
1996	128.6
1997	128.4
1998	128.3
1999	128.2
2000	128.1
2001	128.1
2002	128.1
2003	128.3
2004	128.4
2005	128.6
2006	128.9
2007	129.1
2008	129.4