Year	mm Hg
1980	130.8
1981	130.6
1982	130.5
1983	130.3
1984	130.2
1985	130.1
1986	130
1987	130
1988	130
1989	130
1990	130.1
1991	130.2
1992	130.2
1993	130.2
1994	130.2
1995	130.2
1996	130.3
1997	130.3
1998	130.4
1999	130.5
2000	130.7
2001	131
2002	131.2
2003	131.6
2004	131.9
2005	132.4
2006	132.8
2007	133.2
2008	133.7