Year	mm Hg
1980	136.8
1981	136.2
1982	135.5
1983	134.8
1984	134
1985	133.2
1986	132.6
1987	132
1988	131.4
1989	130.9
1990	130.4
1991	130
1992	129.6
1993	129.2
1994	128.9
1995	128.6
1996	128.3
1997	128.1
1998	128
1999	128
2000	128.1
2001	128.2
2002	128.4
2003	128.5
2004	128.7
2005	128.9
2006	129.1
2007	129.3
2008	129.5