Year	mm Hg
1980	132.8
1981	132.6
1982	132.4
1983	132.2
1984	132
1985	131.8
1986	131.5
1987	131.2
1988	130.8
1989	130.4
1990	130.1
1991	129.7
1992	129.3
1993	129
1994	128.7
1995	128.6
1996	128.5
1997	128.4
1998	128.5
1999	128.6
2000	128.8
2001	129
2002	129.3
2003	129.6
2004	129.9
2005	130.3
2006	130.6
2007	130.9
2008	131.3