Year	mm Hg
1980	128.9
1981	128.7
1982	128.4
1983	128.1
1984	127.9
1985	127.7
1986	127.5
1987	127.3
1988	127.2
1989	127.1
1990	127
1991	126.8
1992	126.7
1993	126.5
1994	126.3
1995	126.1
1996	125.9
1997	125.7
1998	125.6
1999	125.5
2000	125.4
2001	125.3
2002	125.2
2003	125.2
2004	125.2
2005	125.2
2006	125.2
2007	125.2
2008	125.2