Year	Age
1970	1.2
1971	1.3
1972	1.4
1973	1.5
1974	1.6
1975	1.7
1976	1.8
1977	1.9
1978	2.1
1979	2.2
1980	2.3
1981	2.5
1982	2.6
1983	2.8
1984	3
1985	3.1
1986	3.3
1987	3.4
1988	3.6
1989	3.7
1990	3.9
1991	4.1
1992	4.2
1993	4.4
1994	4.6
1995	4.7
1996	4.9
1997	5.1
1998	5.3
1999	5.4
2000	5.6
2001	5.8
2002	5.9
2003	6.1
2004	6.3
2005	6.4
2006	6.6
2007	6.7
2008	6.9
2009	7.1