Year	mm Hg
1980	128.1
1981	128.1
1982	128
1983	127.8
1984	127.7
1985	127.5
1986	127.4
1987	127.2
1988	127
1989	126.7
1990	126.5
1991	126.2
1992	125.9
1993	125.6
1994	125.4
1995	125.1
1996	124.9
1997	124.6
1998	124.4
1999	124.2
2000	124
2001	123.9
2002	123.8
2003	123.7
2004	123.7
2005	123.6
2006	123.6
2007	123.6
2008	123.6