Year	Years
1970	0.8
1971	0.8
1972	0.9
1973	0.9
1974	1
1975	1.1
1976	1.1
1977	1.2
1978	1.3
1979	1.4
1980	1.5
1981	1.6
1982	1.7
1983	1.8
1984	1.9
1985	2
1986	2.1
1987	2.2
1988	2.4
1989	2.5
1990	2.6
1991	2.8
1992	2.9
1993	3.1
1994	3.2
1995	3.4
1996	3.5
1997	3.7
1998	3.8
1999	4
2000	4.2
2001	4.4
2002	4.5
2003	4.7
2004	4.9
2005	5.1
2006	5.3
2007	5.5
2008	5.7
2009	5.9