Year	mm Hg
1980	121.6
1981	121.8
1982	121.9
1983	122.1
1984	122.1
1985	122.2
1986	122.3
1987	122.3
1988	122.4
1989	122.4
1990	122.5
1991	122.6
1992	122.7
1993	122.9
1994	123.1
1995	123.2
1996	123.4
1997	123.6
1998	123.8
1999	123.9
2000	124.1
2001	124.3
2002	124.4
2003	124.5
2004	124.6
2005	124.7
2006	124.8
2007	124.8
2008	124.9