Year	Years
1970	0.3
1971	0.4
1972	0.4
1973	0.4
1974	0.4
1975	0.5
1976	0.5
1977	0.5
1978	0.5
1979	0.6
1980	0.6
1981	0.7
1982	0.7
1983	0.8
1984	0.8
1985	0.9
1986	0.9
1987	1
1988	1.1
1989	1.1
1990	1.2
1991	1.3
1992	1.3
1993	1.4
1994	1.5
1995	1.6
1996	1.7
1997	1.8
1998	1.9
1999	2
2000	2.1
2001	2.2
2002	2.3
2003	2.4
2004	2.5
2005	2.6
2006	2.7
2007	2.8
2008	2.9
2009	3.1