Year	mm Hg
1980	131.1
1981	130.9
1982	130.6
1983	130.4
1984	130.3
1985	130.1
1986	130.1
1987	130
1988	130
1989	130.1
1990	130.1
1991	130.2
1992	130.2
1993	130.2
1994	130.2
1995	130.2
1996	130.1
1997	130.1
1998	130.1
1999	130.2
2000	130.3
2001	130.4
2002	130.5
2003	130.7
2004	131
2005	131.3
2006	131.6
2007	131.9
2008	132.2