Year	Age
1970	0.9
1971	1
1972	1
1973	1.1
1974	1.2
1975	1.2
1976	1.3
1977	1.4
1978	1.5
1979	1.6
1980	1.6
1981	1.7
1982	1.8
1983	2
1984	2.1
1985	2.2
1986	2.3
1987	2.4
1988	2.5
1989	2.7
1990	2.8
1991	2.9
1992	3.1
1993	3.2
1994	3.3
1995	3.5
1996	3.6
1997	3.8
1998	3.9
1999	4.1
2000	4.2
2001	4.4
2002	4.5
2003	4.7
2004	4.9
2005	5
2006	5.2
2007	5.3
2008	5.5
2009	5.7