Year	Age
1970	0.5
1971	0.6
1972	0.6
1973	0.6
1974	0.7
1975	0.7
1976	0.7
1977	0.8
1978	0.8
1979	0.9
1980	1
1981	1
1982	1.1
1983	1.2
1984	1.3
1985	1.5
1986	1.6
1987	1.7
1988	1.8
1989	1.9
1990	2
1991	2.2
1992	2.3
1993	2.4
1994	2.6
1995	2.7
1996	2.8
1997	3
1998	3.1
1999	3.3
2000	3.4
2001	3.5
2002	3.7
2003	3.8
2004	4
2005	4.1
2006	4.3
2007	4.4
2008	4.6
2009	4.7