Year	mm Hg
1980	132.7
1981	132.9
1982	133.1
1983	133.2
1984	133.3
1985	133.3
1986	133.3
1987	133.3
1988	133.2
1989	133.1
1990	133
1991	132.9
1992	132.7
1993	132.5
1994	132.4
1995	132.2
1996	132.1
1997	132.1
1998	132
1999	131.9
2000	131.9
2001	131.8
2002	131.8
2003	131.8
2004	131.7
2005	131.7
2006	131.8
2007	131.7
2008	131.7