Year	mm Hg
1980	131.9
1981	131.8
1982	131.8
1983	131.7
1984	131.7
1985	131.7
1986	131.6
1987	131.6
1988	131.7
1989	131.8
1990	131.9
1991	132
1992	132.2
1993	132.3
1994	132.5
1995	132.7
1996	132.8
1997	132.9
1998	133.1
1999	133.2
2000	133.4
2001	133.5
2002	133.6
2003	133.7
2004	133.8
2005	133.9
2006	134
2007	134.1
2008	134.2