Year	Years
1970	0.94
1971	0.98
1972	1.01
1973	1.05
1974	1.08
1975	1.12
1976	1.16
1977	1.2
1978	1.24
1979	1.28
1980	1.33
1981	1.37
1982	1.42
1983	1.47
1984	1.52
1985	1.57
1986	1.62
1987	1.68
1988	1.74
1989	1.8
1990	1.86
1991	1.92
1992	1.99
1993	2.05
1994	2.12
1995	2.19
1996	2.26
1997	2.33
1998	2.4
1999	2.48
2000	2.55
2001	2.63
2002	2.7
2003	2.78
2004	2.86
2005	2.94
2006	3.03
2007	3.11
2008	3.2
2009	3.29
2010	3.38
2011	3.47
2012	3.57
2013	3.67
2014	3.77
2015	3.87