Year	Years
1970	0.4
1971	0.4
1972	0.4
1973	0.4
1974	0.5
1975	0.5
1976	0.5
1977	0.6
1978	0.6
1979	0.6
1980	0.7
1981	0.7
1982	0.8
1983	0.8
1984	0.9
1985	0.9
1986	1
1987	1
1988	1.1
1989	1.1
1990	1.2
1991	1.3
1992	1.3
1993	1.4
1994	1.5
1995	1.5
1996	1.6
1997	1.7
1998	1.8
1999	1.8
2000	1.9
2001	2
2002	2.1
2003	2.2
2004	2.3
2005	2.4
2006	2.5
2007	2.6
2008	2.7
2009	2.8