Year	Age
1970	8.1
1971	8.3
1972	8.5
1973	8.7
1974	8.8
1975	9
1976	9.2
1977	9.4
1978	9.6
1979	9.7
1980	9.9
1981	10.1
1982	10.3
1983	10.5
1984	10.6
1985	10.8
1986	11
1987	11.1
1988	11.3
1989	11.4
1990	11.6
1991	11.7
1992	11.8
1993	12
1994	12.1
1995	12.2
1996	12.3
1997	12.4
1998	12.5
1999	12.6
2000	12.7
2001	12.8
2002	12.9
2003	13
2004	13.1
2005	13.2
2006	13.3
2007	13.3
2008	13.4
2009	13.5