Year	mm Hg
1980	135.6
1981	134.9
1982	134.2
1983	133.6
1984	133.1
1985	132.5
1986	132.1
1987	131.6
1988	131.2
1989	130.8
1990	130.5
1991	130.3
1992	130
1993	129.9
1994	129.8
1995	129.6
1996	129.5
1997	129.3
1998	129.1
1999	128.9
2000	128.7
2001	128.5
2002	128.3
2003	128.1
2004	128
2005	127.8
2006	127.7
2007	127.5
2008	127.4