Year	Age
1970	8.1
1971	8.3
1972	8.5
1973	8.7
1974	8.9
1975	9.1
1976	9.3
1977	9.5
1978	9.6
1979	9.8
1980	10
1981	10.2
1982	10.3
1983	10.5
1984	10.6
1985	10.7
1986	10.9
1987	11
1988	11.1
1989	11.1
1990	11.2
1991	11.3
1992	11.3
1993	11.4
1994	11.5
1995	11.5
1996	11.6
1997	11.7
1998	11.7
1999	11.8
2000	11.8
2001	11.8
2002	11.9
2003	11.9
2004	11.9
2005	12
2006	12
2007	12
2008	12
2009	12