Year	Years
1970	0.81
1971	0.85
1972	0.88
1973	0.92
1974	0.97
1975	1.01
1976	1.06
1977	1.11
1978	1.16
1979	1.21
1980	1.27
1981	1.33
1982	1.4
1983	1.47
1984	1.54
1985	1.62
1986	1.7
1987	1.79
1988	1.88
1989	1.98
1990	2.09
1991	2.2
1992	2.32
1993	2.45
1994	2.59
1995	2.74
1996	2.89
1997	3.04
1998	3.2
1999	3.35
2000	3.5
2001	3.65
2002	3.81
2003	3.96
2004	4.11
2005	4.25
2006	4.4
2007	4.55
2008	4.7
2009	4.84
2010	4.99
2011	5.13
2012	5.28
2013	5.42
2014	5.56
2015	5.7