Year	mm Hg
1980	133.4
1981	133.2
1982	133.1
1983	132.9
1984	132.7
1985	132.5
1986	132.3
1987	132.3
1988	132.3
1989	132.4
1990	132.5
1991	132.6
1992	132.7
1993	132.8
1994	132.9
1995	133
1996	133.1
1997	133.2
1998	133.4
1999	133.7
2000	134
2001	134.3
2002	134.7
2003	135.2
2004	135.7
2005	136.1
2006	136.6
2007	137
2008	137.5