Year	Years
1970	0.92
1971	0.95
1972	0.98
1973	1.01
1974	1.04
1975	1.08
1976	1.11
1977	1.15
1978	1.19
1979	1.22
1980	1.26
1981	1.3
1982	1.35
1983	1.39
1984	1.43
1985	1.48
1986	1.52
1987	1.57
1988	1.62
1989	1.67
1990	1.72
1991	1.78
1992	1.83
1993	1.89
1994	1.95
1995	2.01
1996	2.07
1997	2.13
1998	2.2
1999	2.27
2000	2.34
2001	2.41
2002	2.48
2003	2.55
2004	2.63
2005	2.71
2006	2.79
2007	2.87
2008	2.96
2009	3.04
2010	3.13
2011	3.22
2012	3.31
2013	3.41
2014	3.51
2015	3.61