Year	mm Hg
1980	134.1
1981	133.8
1982	133.5
1983	133.1
1984	132.7
1985	132.4
1986	132.1
1987	131.8
1988	131.6
1989	131.3
1990	131.1
1991	130.8
1992	130.6
1993	130.3
1994	130.1
1995	129.9
1996	129.7
1997	129.6
1998	129.5
1999	129.5
2000	129.5
2001	129.5
2002	129.6
2003	129.8
2004	130
2005	130.3
2006	130.6
2007	130.9
2008	131.2