Year	mm Hg
1980	134.2
1981	133.8
1982	133.4
1983	133
1984	132.6
1985	132.2
1986	131.9
1987	131.6
1988	131.4
1989	131
1990	130.8
1991	130.5
1992	130.3
1993	130.1
1994	129.9
1995	129.8
1996	129.8
1997	129.8
1998	129.9
1999	130.1
2000	130.3
2001	130.6
2002	131
2003	131.3
2004	131.5
2005	131.8
2006	132.1
2007	132.5
2008	132.8