Year	mm Hg
1980	136.5
1981	136.2
1982	135.9
1983	135.5
1984	135.1
1985	134.7
1986	134.4
1987	134
1988	133.7
1989	133.5
1990	133.2
1991	133
1992	132.8
1993	132.6
1994	132.5
1995	132.4
1996	132.3
1997	132.4
1998	132.4
1999	132.5
2000	132.7
2001	132.8
2002	133
2003	133.3
2004	133.5
2005	133.8
2006	134
2007	134.3
2008	134.6