Year	mm Hg
1980	125.1
1981	125
1982	124.8
1983	124.6
1984	124.5
1985	124.3
1986	124.3
1987	124.2
1988	124.2
1989	124.1
1990	124.1
1991	124
1992	123.9
1993	123.8
1994	123.7
1995	123.6
1996	123.5
1997	123.4
1998	123.3
1999	123.2
2000	123.1
2001	123
2002	122.9
2003	122.8
2004	122.8
2005	122.7
2006	122.6
2007	122.5
2008	122.4