Year	mm Hg
1980	131
1981	131
1982	131
1983	131
1984	131
1985	131
1986	131.1
1987	131.1
1988	131.3
1989	131.5
1990	131.8
1991	132.1
1992	132.4
1993	132.7
1994	132.9
1995	133.1
1996	133.2
1997	133.4
1998	133.6
1999	133.7
2000	133.9
2001	134.1
2002	134.2
2003	134.4
2004	134.6
2005	134.8
2006	135.1
2007	135.3
2008	135.5