Year	mm Hg
1980	128.9
1981	129.2
1982	129.6
1983	129.9
1984	130.2
1985	130.5
1986	130.7
1987	131
1988	131.4
1989	131.7
1990	131.9
1991	132.1
1992	132.1
1993	132.2
1994	132.2
1995	132.2
1996	132.1
1997	132.1
1998	132.1
1999	132.2
2000	132.2
2001	132.3
2002	132.5
2003	132.6
2004	132.7
2005	132.8
2006	132.9
2007	133.1
2008	133.1