Year	mm Hg
1980	129.1
1981	129
1982	128.8
1983	128.6
1984	128.4
1985	128.3
1986	128.1
1987	128
1988	127.9
1989	127.7
1990	127.6
1991	127.4
1992	127.3
1993	127.1
1994	127
1995	126.9
1996	126.8
1997	126.7
1998	126.7
1999	126.6
2000	126.6
2001	126.6
2002	126.5
2003	126.5
2004	126.5
2005	126.4
2006	126.4
2007	126.4
2008	126.4