Year	Age
1970	5.6
1971	5.7
1972	5.9
1973	6
1974	6.2
1975	6.3
1976	6.5
1977	6.6
1978	6.8
1979	7
1980	7.1
1981	7.3
1982	7.4
1983	7.6
1984	7.8
1985	7.9
1986	8.1
1987	8.2
1988	8.3
1989	8.5
1990	8.6
1991	8.8
1992	8.9
1993	9
1994	9.1
1995	9.3
1996	9.4
1997	9.5
1998	9.6
1999	9.7
2000	9.8
2001	9.9
2002	10
2003	10.1
2004	10.2
2005	10.3
2006	10.4
2007	10.5
2008	10.6
2009	10.7