Year	Age
1970	8.5
1971	8.7
1972	8.9
1973	9.1
1974	9.4
1975	9.6
1976	9.8
1977	9.9
1978	10.1
1979	10.3
1980	10.5
1981	10.7
1982	10.8
1983	11
1984	11.1
1985	11.3
1986	11.4
1987	11.5
1988	11.6
1989	11.7
1990	11.9
1991	12
1992	12.1
1993	12.2
1994	12.3
1995	12.3
1996	12.4
1997	12.5
1998	12.6
1999	12.7
2000	12.7
2001	12.8
2002	12.9
2003	12.9
2004	13
2005	13
2006	13.1
2007	13.1
2008	13.2
2009	13.2