Year	mm Hg
1980	134
1981	133.7
1982	133.3
1983	133
1984	132.7
1985	132.4
1986	132.2
1987	132
1988	131.9
1989	131.7
1990	131.6
1991	131.4
1992	131.2
1993	131
1994	130.8
1995	130.6
1996	130.4
1997	130.3
1998	130.3
1999	130.3
2000	130.4
2001	130.5
2002	130.7
2003	130.9
2004	131.2
2005	131.5
2006	131.9
2007	132.3
2008	132.7