Year	Years
1970	0.93
1971	0.97
1972	1
1973	1.04
1974	1.08
1975	1.12
1976	1.16
1977	1.21
1978	1.26
1979	1.31
1980	1.36
1981	1.41
1982	1.47
1983	1.53
1984	1.59
1985	1.66
1986	1.73
1987	1.81
1988	1.89
1989	1.98
1990	2.07
1991	2.17
1992	2.27
1993	2.39
1994	2.51
1995	2.65
1996	2.77
1997	2.89
1998	3.01
1999	3.14
2000	3.26
2001	3.38
2002	3.51
2003	3.64
2004	3.76
2005	3.89
2006	4.02
2007	4.15
2008	4.29
2009	4.42
2010	4.56
2011	4.7
2012	4.84
2013	4.98
2014	5.12
2015	5.26