Year	mm Hg
1980	131.9
1981	131.7
1982	131.5
1983	131.3
1984	131
1985	130.7
1986	130.5
1987	130.2
1988	129.9
1989	129.7
1990	129.5
1991	129.3
1992	129.2
1993	129
1994	128.9
1995	128.7
1996	128.6
1997	128.5
1998	128.4
1999	128.4
2000	128.3
2001	128.3
2002	128.4
2003	128.5
2004	128.6
2005	128.8
2006	129
2007	129.2
2008	129.4