Year	mm Hg
1980	130.4
1981	130.3
1982	130.2
1983	130
1984	129.8
1985	129.7
1986	129.6
1987	129.4
1988	129.3
1989	129.2
1990	129.1
1991	128.9
1992	128.7
1993	128.5
1994	128.3
1995	128.2
1996	128
1997	127.9
1998	127.9
1999	127.9
2000	127.9
2001	128
2002	128
2003	128.1
2004	128.3
2005	128.6
2006	128.9
2007	129.2
2008	129.6