Year	mm Hg
1980	138.4
1981	137.9
1982	137.4
1983	136.9
1984	136.4
1985	135.9
1986	135.5
1987	135.1
1988	134.7
1989	134.4
1990	134.1
1991	133.7
1992	133.3
1993	132.9
1994	132.4
1995	131.9
1996	131.4
1997	130.9
1998	130.4
1999	129.9
2000	129.5
2001	129.1
2002	128.7
2003	128.3
2004	128
2005	127.6
2006	127.3
2007	126.9
2008	126.6