Year	mm Hg
1980	129.8
1981	129.8
1982	129.7
1983	129.6
1984	129.5
1985	129.3
1986	129.2
1987	129.1
1988	129
1989	128.9
1990	128.8
1991	128.7
1992	128.6
1993	128.5
1994	128.4
1995	128.4
1996	128.3
1997	128.2
1998	128.2
1999	128.2
2000	128.3
2001	128.4
2002	128.5
2003	128.6
2004	128.7
2005	128.8
2006	128.8
2007	128.9
2008	128.9