Year	mm Hg
1980	129.7
1981	129.7
1982	129.7
1983	129.6
1984	129.5
1985	129.4
1986	129.4
1987	129.3
1988	129.2
1989	129.2
1990	129.2
1991	129.2
1992	129.2
1993	129.2
1994	129.2
1995	129.2
1996	129.2
1997	129.3
1998	129.4
1999	129.4
2000	129.5
2001	129.7
2002	129.8
2003	129.9
2004	130
2005	130.1
2006	130.3
2007	130.4
2008	130.6