Year	Age
1970	0.9
1971	1
1972	1
1973	1.1
1974	1.1
1975	1.2
1976	1.2
1977	1.3
1978	1.4
1979	1.4
1980	1.5
1981	1.6
1982	1.7
1983	1.8
1984	1.9
1985	2
1986	2
1987	2.1
1988	2.2
1989	2.3
1990	2.4
1991	2.5
1992	2.6
1993	2.7
1994	2.8
1995	2.9
1996	3
1997	3.1
1998	3.2
1999	3.4
2000	3.5
2001	3.6
2002	3.7
2003	3.8
2004	3.9
2005	4
2006	4.1
2007	4.3
2008	4.4
2009	4.5