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	2.4
1979	2.5
1980	2.7
1981	2.8
1982	3
1983	3.2
1984	3.4
1985	3.5
1986	3.7
1987	3.9
1988	4.1
1989	4.2
1990	4.4
1991	4.6
1992	4.8
1993	5
1994	5.2
1995	5.4
1996	5.6
1997	5.8
1998	6
1999	6.2
2000	6.4
2001	6.6
2002	6.8
2003	7
2004	7.2
2005	7.4
2006	7.6
2007	7.8
2008	8
2009	8.2