Year	mm Hg
1980	134.1
1981	133.9
1982	133.7
1983	133.4
1984	133.1
1985	132.8
1986	132.5
1987	132.3
1988	132.2
1989	132.1
1990	132
1991	131.9
1992	131.9
1993	131.8
1994	131.8
1995	131.7
1996	131.8
1997	131.9
1998	132
1999	132.2
2000	132.3
2001	132.5
2002	132.7
2003	133
2004	133.4
2005	133.7
2006	134.2
2007	134.6
2008	135