Year	mm Hg
1980	134.3
1981	134
1982	133.6
1983	133.2
1984	132.8
1985	132.4
1986	132.1
1987	131.8
1988	131.5
1989	131.3
1990	131.1
1991	130.9
1992	130.8
1993	130.6
1994	130.5
1995	130.4
1996	130.4
1997	130.5
1998	130.6
1999	130.7
2000	130.9
2001	131
2002	131.2
2003	131.5
2004	131.8
2005	132.1
2006	132.4
2007	132.7
2008	133