Year	Age
1970	1.1
1971	1.2
1972	1.2
1973	1.3
1974	1.4
1975	1.5
1976	1.6
1977	1.6
1978	1.7
1979	1.8
1980	1.9
1981	2
1982	2.1
1983	2.2
1984	2.3
1985	2.4
1986	2.5
1987	2.6
1988	2.7
1989	2.9
1990	3
1991	3.1
1992	3.2
1993	3.3
1994	3.5
1995	3.6
1996	3.7
1997	3.9
1998	4
1999	4.2
2000	4.3
2001	4.4
2002	4.6
2003	4.7
2004	4.9
2005	5
2006	5.2
2007	5.3
2008	5.5
2009	5.7