Year	mm Hg
1980	118.3
1981	118.5
1982	118.5
1983	118.6
1984	118.7
1985	118.7
1986	118.8
1987	118.9
1988	119
1989	119.2
1990	119.3
1991	119.5
1992	119.6
1993	119.8
1994	120
1995	120.1
1996	120.2
1997	120.3
1998	120.4
1999	120.4
2000	120.5
2001	120.5
2002	120.5
2003	120.6
2004	120.6
2005	120.6
2006	120.6
2007	120.6
2008	120.5