Year	mm Hg
1980	124.5
1981	124.2
1982	123.8
1983	123.5
1984	123.2
1985	122.8
1986	122.6
1987	122.3
1988	122.1
1989	121.8
1990	121.5
1991	121.3
1992	121.2
1993	121
1994	120.9
1995	120.7
1996	120.5
1997	120.4
1998	120.3
1999	120.1
2000	119.9
2001	119.8
2002	119.7
2003	119.5
2004	119.4
2005	119.3
2006	119.1
2007	119
2008	118.9