Year	mm Hg
1980	122.1
1981	122.3
1982	122.6
1983	122.8
1984	123.1
1985	123.3
1986	123.6
1987	123.9
1988	124.1
1989	124.3
1990	124.5
1991	124.6
1992	124.7
1993	124.7
1994	124.8
1995	124.9
1996	124.9
1997	124.9
1998	125
1999	125
2000	125
2001	125
2002	125
2003	124.9
2004	124.8
2005	124.6
2006	124.4
2007	124.2
2008	123.9