Year	Age
1970	0.8
1971	0.9
1972	0.9
1973	1
1974	1
1975	1.1
1976	1.1
1977	1.2
1978	1.3
1979	1.3
1980	1.4
1981	1.5
1982	1.6
1983	1.7
1984	1.8
1985	1.9
1986	1.9
1987	2
1988	2.1
1989	2.2
1990	2.3
1991	2.4
1992	2.5
1993	2.6
1994	2.7
1995	2.8
1996	2.9
1997	3
1998	3.2
1999	3.3
2000	3.4
2001	3.5
2002	3.6
2003	3.7
2004	3.8
2005	3.9
2006	4
2007	4.2
2008	4.3
2009	4.4