Year	Age
1970	7.3
1971	7.7
1972	8
1973	8.3
1974	8.6
1975	8.9
1976	9.2
1977	9.4
1978	9.7
1979	10
1980	10.2
1981	10.5
1982	10.7
1983	10.9
1984	11.1
1985	11.3
1986	11.5
1987	11.7
1988	11.8
1989	12
1990	12.1
1991	12.3
1992	12.4
1993	12.6
1994	12.7
1995	12.9
1996	13
1997	13.1
1998	13.2
1999	13.3
2000	13.5
2001	13.6
2002	13.7
2003	13.7
2004	13.8
2005	13.9
2006	14
2007	14.1
2008	14.1
2009	14.2