Year	mm Hg
1980	131.8
1981	131.9
1982	132
1983	132
1984	132
1985	131.9
1986	131.9
1987	132
1988	132
1989	132.1
1990	132.1
1991	132.1
1992	132.1
1993	132.1
1994	131.9
1995	131.9
1996	132
1997	132.1
1998	132.3
1999	132.5
2000	132.8
2001	133.1
2002	133.5
2003	133.9
2004	134.3
2005	134.7
2006	135.1
2007	135.5
2008	136