Year	Years
1970	0.68
1971	0.7
1972	0.72
1973	0.75
1974	0.77
1975	0.8
1976	0.83
1977	0.85
1978	0.88
1979	0.91
1980	0.95
1981	0.98
1982	1.02
1983	1.05
1984	1.09
1985	1.13
1986	1.17
1987	1.22
1988	1.27
1989	1.32
1990	1.37
1991	1.42
1992	1.48
1993	1.54
1994	1.6
1995	1.67
1996	1.73
1997	1.79
1998	1.86
1999	1.93
2000	1.99
2001	2.06
2002	2.13
2003	2.2
2004	2.27
2005	2.34
2006	2.41
2007	2.48
2008	2.56
2009	2.63
2010	2.71
2011	2.79
2012	2.86
2013	2.94
2014	3.02
2015	3.1