Year	mm Hg
1980	129.7
1981	129.4
1982	129.2
1983	128.9
1984	128.6
1985	128.4
1986	128.2
1987	128
1988	127.8
1989	127.5
1990	127.2
1991	126.8
1992	126.5
1993	126.2
1994	125.9
1995	125.8
1996	125.6
1997	125.5
1998	125.4
1999	125.3
2000	125.3
2001	125.2
2002	125.2
2003	125.2
2004	125.3
2005	125.3
2006	125.4
2007	125.5
2008	125.6