Year	mm Hg
1980	133.9
1981	133.9
1982	133.9
1983	133.9
1984	133.8
1985	133.8
1986	133.8
1987	133.7
1988	133.6
1989	133.5
1990	133.4
1991	133.1
1992	132.7
1993	132.3
1994	131.9
1995	131.4
1996	131.1
1997	130.8
1998	130.6
1999	130.5
2000	130.5
2001	130.6
2002	130.8
2003	131
2004	131.2
2005	131.5
2006	131.7
2007	132.1
2008	132.4