Year	mm Hg
1980	135.2
1981	135
1982	134.8
1983	134.6
1984	134.4
1985	134.2
1986	133.9
1987	133.7
1988	133.6
1989	133.5
1990	133.4
1991	133.3
1992	133.2
1993	133.1
1994	133
1995	133
1996	133.1
1997	133.3
1998	133.6
1999	134
2000	134.3
2001	134.7
2002	135.1
2003	135.4
2004	135.7
2005	136
2006	136.1
2007	136.3
2008	136.4