Year	mm Hg
1980	133.7
1981	133.5
1982	133.3
1983	133
1984	132.8
1985	132.6
1986	132.4
1987	132.2
1988	132.1
1989	132
1990	131.9
1991	131.8
1992	131.7
1993	131.6
1994	131.5
1995	131.5
1996	131.5
1997	131.5
1998	131.6
1999	131.7
2000	131.8
2001	132
2002	132.2
2003	132.3
2004	132.5
2005	132.7
2006	132.9
2007	133.1
2008	133.3