Year	Years
1970	0.93
1971	0.97
1972	1
1973	1.03
1974	1.07
1975	1.11
1976	1.15
1977	1.19
1978	1.23
1979	1.27
1980	1.31
1981	1.36
1982	1.41
1983	1.46
1984	1.51
1985	1.56
1986	1.62
1987	1.67
1988	1.73
1989	1.79
1990	1.86
1991	1.92
1992	1.99
1993	2.06
1994	2.13
1995	2.21
1996	2.29
1997	2.37
1998	2.45
1999	2.53
2000	2.62
2001	2.71
2002	2.79
2003	2.88
2004	2.97
2005	3.07
2006	3.16
2007	3.26
2008	3.35
2009	3.45
2010	3.55
2011	3.65
2012	3.76
2013	3.86
2014	3.97
2015	4.07