Year	mm Hg
1980	136.2
1981	136.1
1982	135.9
1983	135.7
1984	135.5
1985	135.3
1986	135
1987	134.8
1988	134.6
1989	134.4
1990	134.1
1991	133.8
1992	133.5
1993	133.1
1994	132.8
1995	132.6
1996	132.4
1997	132.2
1998	132.1
1999	131.9
2000	131.7
2001	131.6
2002	131.4
2003	131.3
2004	131.1
2005	130.9
2006	130.7
2007	130.6
2008	130.4