Year	Age
1970	8.7
1971	8.9
1972	9
1973	9.2
1974	9.3
1975	9.5
1976	9.6
1977	9.8
1978	9.9
1979	10
1980	10.2
1981	10.3
1982	10.4
1983	10.5
1984	10.7
1985	10.8
1986	10.9
1987	10.9
1988	11
1989	11.1
1990	11.2
1991	11.3
1992	11.3
1993	11.4
1994	11.5
1995	11.6
1996	11.6
1997	11.7
1998	11.8
1999	11.8
2000	11.9
2001	12
2002	12
2003	12.1
2004	12.1
2005	12.2
2006	12.2
2007	12.3
2008	12.3
2009	12.4