Year	mm Hg
1980	134.4
1981	133.9
1982	133.4
1983	132.8
1984	132.3
1985	131.7
1986	131.2
1987	130.7
1988	130.3
1989	129.8
1990	129.4
1991	129
1992	128.6
1993	128.2
1994	127.8
1995	127.5
1996	127.2
1997	127
1998	126.8
1999	126.7
2000	126.7
2001	126.7
2002	126.7
2003	126.8
2004	127
2005	127.2
2006	127.3
2007	127.5
2008	127.6