Year	Years
1970	1.39
1971	1.44
1972	1.49
1973	1.54
1974	1.59
1975	1.64
1976	1.69
1977	1.75
1978	1.81
1979	1.87
1980	1.93
1981	1.99
1982	2.06
1983	2.13
1984	2.2
1985	2.27
1986	2.35
1987	2.43
1988	2.51
1989	2.59
1990	2.68
1991	2.77
1992	2.87
1993	2.97
1994	3.07
1995	3.18
1996	3.29
1997	3.41
1998	3.53
1999	3.66
2000	3.78
2001	3.91
2002	4.04
2003	4.17
2004	4.3
2005	4.44
2006	4.57
2007	4.71
2008	4.84
2009	4.98
2010	5.12
2011	5.26
2012	5.4
2013	5.54
2014	5.68
2015	5.82