Year	mm Hg
1980	125.7
1981	125.6
1982	125.5
1983	125.4
1984	125.3
1985	125.2
1986	125.1
1987	125
1988	125
1989	125
1990	124.9
1991	124.8
1992	124.8
1993	124.8
1994	124.7
1995	124.7
1996	124.7
1997	124.8
1998	124.9
1999	125
2000	125.1
2001	125.3
2002	125.4
2003	125.5
2004	125.6
2005	125.7
2006	125.8
2007	125.8
2008	125.9