Year	Years
1970	1.09
1971	1.12
1972	1.16
1973	1.19
1974	1.23
1975	1.27
1976	1.3
1977	1.34
1978	1.39
1979	1.43
1980	1.47
1981	1.51
1982	1.56
1983	1.61
1984	1.65
1985	1.7
1986	1.75
1987	1.8
1988	1.85
1989	1.91
1990	1.96
1991	2.02
1992	2.08
1993	2.13
1994	2.19
1995	2.25
1996	2.32
1997	2.39
1998	2.46
1999	2.53
2000	2.61
2001	2.69
2002	2.76
2003	2.84
2004	2.93
2005	3.01
2006	3.1
2007	3.18
2008	3.27
2009	3.37
2010	3.46
2011	3.56
2012	3.66
2013	3.76
2014	3.86
2015	3.97