Year	mm Hg
1980	130.6
1981	130.5
1982	130.4
1983	130.3
1984	130.2
1985	130.1
1986	130
1987	130
1988	129.9
1989	129.8
1990	129.8
1991	129.7
1992	129.6
1993	129.4
1994	129.3
1995	129.2
1996	129.1
1997	129
1998	128.9
1999	128.8
2000	128.7
2001	128.7
2002	128.7
2003	128.7
2004	128.8
2005	128.9
2006	129.1
2007	129.2
2008	129.3