Year	Years
1970	1.69
1971	1.73
1972	1.78
1973	1.82
1974	1.87
1975	1.92
1976	1.97
1977	2.02
1978	2.07
1979	2.13
1980	2.18
1981	2.24
1982	2.3
1983	2.36
1984	2.42
1985	2.48
1986	2.54
1987	2.61
1988	2.67
1989	2.74
1990	2.81
1991	2.88
1992	2.96
1993	3.03
1994	3.11
1995	3.18
1996	3.26
1997	3.35
1998	3.43
1999	3.52
2000	3.6
2001	3.69
2002	3.78
2003	3.87
2004	3.96
2005	4.05
2006	4.15
2007	4.24
2008	4.34
2009	4.44
2010	4.54
2011	4.64
2012	4.74
2013	4.84
2014	4.95
2015	5.05