Year	Years
1970	0.69
1971	0.71
1972	0.74
1973	0.76
1974	0.79
1975	0.82
1976	0.85
1977	0.88
1978	0.91
1979	0.94
1980	0.97
1981	1.01
1982	1.05
1983	1.08
1984	1.12
1985	1.16
1986	1.2
1987	1.25
1988	1.29
1989	1.34
1990	1.39
1991	1.44
1992	1.49
1993	1.55
1994	1.6
1995	1.66
1996	1.73
1997	1.8
1998	1.87
1999	1.94
2000	2.01
2001	2.08
2002	2.16
2003	2.23
2004	2.31
2005	2.39
2006	2.47
2007	2.55
2008	2.63
2009	2.72
2010	2.8
2011	2.89
2012	2.98
2013	3.07
2014	3.17
2015	3.26