Year	mm Hg
1980	131.6
1981	131
1982	130.4
1983	129.9
1984	129.5
1985	129.1
1986	128.6
1987	128.2
1988	127.8
1989	127.4
1990	127.1
1991	126.9
1992	126.6
1993	126.4
1994	126.2
1995	126.2
1996	126.1
1997	126.1
1998	126.1
1999	126.2
2000	126.3
2001	126.5
2002	126.7
2003	126.9
2004	127.2
2005	127.4
2006	127.7
2007	127.9
2008	128.2