Year	Age
1970	1.4
1971	1.4
1972	1.5
1973	1.6
1974	1.7
1975	1.8
1976	1.9
1977	2.1
1978	2.2
1979	2.4
1980	2.5
1981	2.7
1982	2.9
1983	3.1
1984	3.3
1985	3.5
1986	3.7
1987	3.9
1988	4.1
1989	4.3
1990	4.6
1991	4.8
1992	5
1993	5.2
1994	5.4
1995	5.6
1996	5.8
1997	6.1
1998	6.3
1999	6.5
2000	6.7
2001	6.9
2002	7.1
2003	7.3
2004	7.5
2005	7.7
2006	7.9
2007	8.1
2008	8.3
2009	8.5