Year	mm Hg
1980	134.9
1981	134.8
1982	134.6
1983	134.4
1984	134.2
1985	133.9
1986	133.7
1987	133.5
1988	133.3
1989	133.1
1990	132.9
1991	132.7
1992	132.5
1993	132.2
1994	131.9
1995	131.7
1996	131.4
1997	131.2
1998	131
1999	130.9
2000	130.9
2001	130.7
2002	130.5
2003	130.4
2004	130.4
2005	130.3
2006	130.2
2007	130
2008	129.9