Year	mm Hg
1980	133.2
1981	132.9
1982	132.6
1983	132.3
1984	132
1985	131.6
1986	131.4
1987	131.2
1988	131.1
1989	130.9
1990	130.7
1991	130.5
1992	130.5
1993	130.3
1994	130.3
1995	130.2
1996	130.2
1997	130.2
1998	130.3
1999	130.4
2000	130.6
2001	130.8
2002	131
2003	131.2
2004	131.5
2005	131.7
2006	132
2007	132.2
2008	132.5