Year	mm Hg
1980	136.6
1981	136
1982	135.4
1983	134.8
1984	134.2
1985	133.8
1986	133.4
1987	133.2
1988	133
1989	132.9
1990	132.8
1991	132.8
1992	132.7
1993	132.5
1994	132.4
1995	132.3
1996	132.2
1997	132
1998	131.8
1999	131.6
2000	131.4
2001	131.2
2002	131
2003	130.8
2004	130.6
2005	130.4
2006	130.2
2007	130
2008	129.7