Year	mm Hg
1980	120.9
1981	121.2
1982	121.5
1983	121.8
1984	122.2
1985	122.5
1986	122.8
1987	123.1
1988	123.4
1989	123.7
1990	123.9
1991	124.1
1992	124.3
1993	124.4
1994	124.5
1995	124.5
1996	124.6
1997	124.6
1998	124.6
1999	124.5
2000	124.5
2001	124.4
2002	124.3
2003	124.2
2004	124
2005	123.8
2006	123.6
2007	123.4
2008	123.1