Year	mm Hg
1980	133.6
1981	133.4
1982	133.2
1983	132.9
1984	132.7
1985	132.4
1986	132.2
1987	132
1988	131.8
1989	131.6
1990	131.4
1991	131.2
1992	131
1993	130.9
1994	130.8
1995	130.7
1996	130.7
1997	130.7
1998	130.7
1999	130.9
2000	131
2001	131.3
2002	131.5
2003	131.7
2004	132
2005	132.2
2006	132.4
2007	132.6
2008	132.8