Year	Age
1970	1
1971	1.1
1972	1.2
1973	1.2
1974	1.3
1975	1.4
1976	1.4
1977	1.5
1978	1.6
1979	1.7
1980	1.7
1981	1.8
1982	1.9
1983	2
1984	2.1
1985	2.2
1986	2.3
1987	2.4
1988	2.5
1989	2.5
1990	2.6
1991	2.7
1992	2.8
1993	2.9
1994	3
1995	3.2
1996	3.3
1997	3.4
1998	3.5
1999	3.6
2000	3.7
2001	3.8
2002	3.9
2003	4
2004	4.2
2005	4.3
2006	4.4
2007	4.5
2008	4.6
2009	4.7