Year	Years
1970	1.18
1971	1.23
1972	1.29
1973	1.35
1974	1.4
1975	1.47
1976	1.53
1977	1.6
1978	1.67
1979	1.74
1980	1.82
1981	1.89
1982	1.97
1983	2.06
1984	2.14
1985	2.23
1986	2.32
1987	2.41
1988	2.51
1989	2.61
1990	2.71
1991	2.82
1992	2.94
1993	3.05
1994	3.18
1995	3.31
1996	3.43
1997	3.55
1998	3.67
1999	3.79
2000	3.91
2001	4.03
2002	4.15
2003	4.27
2004	4.39
2005	4.51
2006	4.63
2007	4.75
2008	4.87
2009	4.99
2010	5.1
2011	5.22
2012	5.34
2013	5.46
2014	5.58
2015	5.7