Year	mm Hg
1980	128.5
1981	128.3
1982	128.1
1983	127.9
1984	127.7
1985	127.4
1986	127.2
1987	127
1988	126.8
1989	126.6
1990	126.4
1991	126.3
1992	126.1
1993	126
1994	125.9
1995	125.8
1996	125.7
1997	125.7
1998	125.8
1999	125.8
2000	126
2001	126.1
2002	126.3
2003	126.5
2004	126.8
2005	127.2
2006	127.6
2007	128
2008	128.4