Year	mm Hg
1980	130.5
1981	130.3
1982	130.1
1983	129.9
1984	129.7
1985	129.5
1986	129.4
1987	129.2
1988	129.1
1989	129.1
1990	129
1991	128.9
1992	128.8
1993	128.8
1994	128.7
1995	128.7
1996	128.8
1997	128.8
1998	128.9
1999	129
2000	129.1
2001	129.1
2002	129.2
2003	129.3
2004	129.3
2005	129.4
2006	129.4
2007	129.4
2008	129.5