Year	Years
1970	1.19
1971	1.24
1972	1.29
1973	1.34
1974	1.39
1975	1.45
1976	1.51
1977	1.58
1978	1.64
1979	1.71
1980	1.79
1981	1.86
1982	1.95
1983	2.03
1984	2.12
1985	2.22
1986	2.32
1987	2.43
1988	2.55
1989	2.67
1990	2.8
1991	2.93
1992	3.08
1993	3.23
1994	3.4
1995	3.57
1996	3.71
1997	3.85
1998	3.99
1999	4.14
2000	4.28
2001	4.42
2002	4.57
2003	4.71
2004	4.86
2005	5.01
2006	5.15
2007	5.3
2008	5.45
2009	5.6
2010	5.75
2011	5.9
2012	6.05
2013	6.2
2014	6.35
2015	6.51