Year	mm Hg
1980	129.7
1981	129.7
1982	129.7
1983	129.6
1984	129.5
1985	129.4
1986	129.3
1987	129.2
1988	129.2
1989	129.3
1990	129.3
1991	129.3
1992	129.4
1993	129.5
1994	129.5
1995	129.6
1996	129.7
1997	129.8
1998	130
1999	130.2
2000	130.5
2001	130.8
2002	131.2
2003	131.5
2004	132
2005	132.4
2006	132.8
2007	133.2
2008	133.6