Year	mm Hg
1980	134.5
1981	134
1982	133.5
1983	133
1984	132.5
1985	132
1986	131.4
1987	131
1988	130.6
1989	130.3
1990	130.1
1991	129.9
1992	129.8
1993	129.6
1994	129.5
1995	129.4
1996	129.5
1997	129.5
1998	129.6
1999	129.8
2000	130
2001	130.3
2002	130.6
2003	130.9
2004	131.3
2005	131.7
2006	132.1
2007	132.5
2008	132.8