Year	mm Hg
1980	128.8
1981	129
1982	129.2
1983	129.3
1984	129.4
1985	129.6
1986	129.8
1987	130
1988	130.2
1989	130.4
1990	130.5
1991	130.6
1992	130.6
1993	130.6
1994	130.6
1995	130.5
1996	130.5
1997	130.5
1998	130.4
1999	130.4
2000	130.5
2001	130.6
2002	130.8
2003	130.9
2004	131.1
2005	131.3
2006	131.5
2007	131.7
2008	131.9