Year	mm Hg
1980	135.1
1981	135
1982	135
1983	134.9
1984	134.9
1985	134.8
1986	134.7
1987	134.6
1988	134.4
1989	134.2
1990	134
1991	133.7
1992	133.3
1993	133
1994	132.6
1995	132.3
1996	132
1997	131.7
1998	131.5
1999	131.4
2000	131.5
2001	131.5
2002	131.7
2003	131.9
2004	132.1
2005	132.3
2006	132.5
2007	132.8
2008	133