Year	Age
1970	1.1
1971	1.1
1972	1.2
1973	1.3
1974	1.4
1975	1.4
1976	1.5
1977	1.6
1978	1.7
1979	1.8
1980	1.9
1981	2
1982	2.2
1983	2.3
1984	2.4
1985	2.6
1986	2.7
1987	2.8
1988	3
1989	3.1
1990	3.3
1991	3.4
1992	3.6
1993	3.7
1994	3.9
1995	4
1996	4.2
1997	4.3
1998	4.5
1999	4.6
2000	4.8
2001	4.9
2002	5.1
2003	5.3
2004	5.4
2005	5.6
2006	5.7
2007	5.9
2008	6
2009	6.2