Year	Age
1970	5.8
1971	5.9
1972	6.1
1973	6.3
1974	6.5
1975	6.6
1976	6.8
1977	7
1978	7.1
1979	7.3
1980	7.4
1981	7.6
1982	7.7
1983	7.9
1984	8
1985	8.2
1986	8.4
1987	8.5
1988	8.7
1989	8.8
1990	8.9
1991	9.1
1992	9.2
1993	9.4
1994	9.5
1995	9.7
1996	9.8
1997	9.9
1998	10.1
1999	10.2
2000	10.3
2001	10.4
2002	10.6
2003	10.7
2004	10.8
2005	10.9
2006	11
2007	11.1
2008	11.2
2009	11.3