Year	Years
1970	0.7
1971	0.73
1972	0.76
1973	0.78
1974	0.81
1975	0.85
1976	0.88
1977	0.92
1978	0.95
1979	0.99
1980	1.03
1981	1.07
1982	1.12
1983	1.16
1984	1.21
1985	1.26
1986	1.32
1987	1.37
1988	1.43
1989	1.49
1990	1.56
1991	1.63
1992	1.7
1993	1.78
1994	1.86
1995	1.94
1996	2.03
1997	2.13
1998	2.23
1999	2.34
2000	2.44
2001	2.55
2002	2.67
2003	2.78
2004	2.9
2005	3.02
2006	3.14
2007	3.27
2008	3.39
2009	3.51
2010	3.63
2011	3.75
2012	3.87
2013	3.99
2014	4.1
2015	4.22