Year	Years
1970	0.76
1971	0.78
1972	0.8
1973	0.83
1974	0.86
1975	0.89
1976	0.91
1977	0.94
1978	0.97
1979	1
1980	1.04
1981	1.07
1982	1.1
1983	1.14
1984	1.17
1985	1.21
1986	1.25
1987	1.29
1988	1.33
1989	1.37
1990	1.41
1991	1.45
1992	1.49
1993	1.54
1994	1.59
1995	1.63
1996	1.68
1997	1.73
1998	1.78
1999	1.84
2000	1.89
2001	1.95
2002	2.01
2003	2.07
2004	2.13
2005	2.2
2006	2.26
2007	2.33
2008	2.4
2009	2.47
2010	2.54
2011	2.62
2012	2.69
2013	2.77
2014	2.85
2015	2.94