Year	mm Hg
1980	131.2
1981	130.7
1982	130.2
1983	129.8
1984	129.3
1985	128.9
1986	128.6
1987	128.2
1988	128
1989	127.7
1990	127.4
1991	127
1992	126.7
1993	126.3
1994	125.9
1995	125.6
1996	125.2
1997	124.9
1998	124.7
1999	124.5
2000	124.3
2001	124.1
2002	123.9
2003	123.8
2004	123.7
2005	123.6
2006	123.5
2007	123.4
2008	123.3