Year	Age
1970	1.5
1971	1.6
1972	1.7
1973	1.8
1974	1.9
1975	2
1976	2.1
1977	2.2
1978	2.4
1979	2.5
1980	2.6
1981	2.8
1982	2.9
1983	3.1
1984	3.2
1985	3.4
1986	3.5
1987	3.7
1988	3.8
1989	4
1990	4.2
1991	4.3
1992	4.5
1993	4.7
1994	4.8
1995	5
1996	5.2
1997	5.4
1998	5.6
1999	5.7
2000	5.9
2001	6.1
2002	6.3
2003	6.5
2004	6.7
2005	6.8
2006	7
2007	7.2
2008	7.4
2009	7.6