Year	mm Hg
1980	140.9
1981	140.1
1982	139.4
1983	138.6
1984	138
1985	137.3
1986	136.8
1987	136.4
1988	136.1
1989	135.8
1990	135.5
1991	135.3
1992	135
1993	134.7
1994	134.4
1995	134.1
1996	133.8
1997	133.6
1998	133.3
1999	133.1
2000	132.9
2001	132.7
2002	132.5
2003	132.4
2004	132.2
2005	132
2006	131.9
2007	131.7
2008	131.6