Year	mm Hg
1980	141.7
1981	141
1982	140.2
1983	139.5
1984	138.7
1985	137.9
1986	137.1
1987	136.4
1988	135.6
1989	134.9
1990	134.2
1991	133.6
1992	133.1
1993	132.6
1994	132.2
1995	131.9
1996	131.8
1997	131.7
1998	131.7
1999	131.9
2000	132.1
2001	132.5
2002	132.9
2003	133.4
2004	133.9
2005	134.5
2006	135.2
2007	135.9
2008	136.6