Year	mm Hg
1980	130.5
1981	130.4
1982	130.4
1983	130.3
1984	130.3
1985	130.2
1986	130.1
1987	130.1
1988	130
1989	130
1990	129.9
1991	129.8
1992	129.6
1993	129.3
1994	129.1
1995	128.8
1996	128.6
1997	128.5
1998	128.4
1999	128.4
2000	128.5
2001	128.6
2002	128.7
2003	128.8
2004	129
2005	129.2
2006	129.3
2007	129.5
2008	129.6