Year	mm Hg
1980	120.6
1981	120.6
1982	120.8
1983	120.9
1984	121
1985	121.1
1986	121.2
1987	121.4
1988	121.6
1989	121.9
1990	122.1
1991	122.3
1992	122.5
1993	122.4
1994	122.4
1995	122.2
1996	122.1
1997	121.8
1998	121.6
1999	121.3
2000	121
2001	120.7
2002	120.2
2003	119.8
2004	119.3
2005	118.7
2006	118.1
2007	117.5
2008	116.9