Year	mm Hg
1980	133.2
1981	133
1982	132.8
1983	132.6
1984	132.4
1985	132.2
1986	131.9
1987	131.7
1988	131.6
1989	131.4
1990	131.4
1991	131.4
1992	131.6
1993	131.8
1994	132
1995	132.3
1996	132.5
1997	132.8
1998	132.9
1999	133.1
2000	133.3
2001	133.5
2002	133.7
2003	133.9
2004	134
2005	134.3
2006	134.6
2007	134.9
2008	135.2