Year	mm Hg
1980	130
1981	130.1
1982	130.2
1983	130.2
1984	130.3
1985	130.3
1986	130.4
1987	130.4
1988	130.4
1989	130.3
1990	130.4
1991	130.4
1992	130.4
1993	130.4
1994	130.3
1995	130.2
1996	130.2
1997	130.1
1998	130
1999	130
2000	129.9
2001	129.7
2002	129.6
2003	129.4
2004	129.3
2005	129.1
2006	129
2007	128.8
2008	128.6