Year	Age
1970	1.3
1971	1.3
1972	1.4
1973	1.5
1974	1.6
1975	1.7
1976	1.8
1977	1.8
1978	1.9
1979	2
1980	2.1
1981	2.2
1982	2.3
1983	2.4
1984	2.6
1985	2.7
1986	2.8
1987	2.9
1988	3
1989	3.1
1990	3.2
1991	3.3
1992	3.4
1993	3.6
1994	3.7
1995	3.8
1996	3.9
1997	4
1998	4.2
1999	4.3
2000	4.4
2001	4.5
2002	4.6
2003	4.8
2004	4.9
2005	5
2006	5.1
2007	5.2
2008	5.4
2009	5.5