Year	Age
1970	1.4
1971	1.5
1972	1.6
1973	1.7
1974	1.8
1975	1.9
1976	2.1
1977	2.2
1978	2.3
1979	2.4
1980	2.6
1981	2.7
1982	2.9
1983	3
1984	3.2
1985	3.3
1986	3.5
1987	3.7
1988	3.8
1989	4
1990	4.1
1991	4.3
1992	4.5
1993	4.6
1994	4.8
1995	4.9
1996	5.1
1997	5.3
1998	5.4
1999	5.6
2000	5.8
2001	5.9
2002	6.1
2003	6.2
2004	6.4
2005	6.5
2006	6.7
2007	6.8
2008	6.9
2009	7.1