Year	mm Hg
1980	132.3
1981	132.4
1982	132.4
1983	132.3
1984	132.3
1985	132.2
1986	132.2
1987	132.1
1988	132
1989	132
1990	131.9
1991	131.7
1992	131.4
1993	131.2
1994	130.8
1995	130.5
1996	130.2
1997	129.9
1998	129.7
1999	129.6
2000	129.6
2001	129.5
2002	129.5
2003	129.6
2004	129.6
2005	129.7
2006	129.8
2007	129.9
2008	129.9