Year	mm Hg
1980	136.5
1981	136.4
1982	136.2
1983	136
1984	135.8
1985	135.5
1986	135.3
1987	135
1988	134.7
1989	134.3
1990	133.9
1991	133.4
1992	132.7
1993	132.1
1994	131.6
1995	131.1
1996	130.9
1997	130.7
1998	130.5
1999	130.4
2000	130.3
2001	130.3
2002	130.2
2003	130.2
2004	130.1
2005	130
2006	129.9
2007	129.7
2008	129.6