Year	Years
1970	0.58
1971	0.6
1972	0.62
1973	0.64
1974	0.67
1975	0.69
1976	0.71
1977	0.74
1978	0.76
1979	0.79
1980	0.82
1981	0.85
1982	0.88
1983	0.91
1984	0.94
1985	0.98
1986	1.01
1987	1.05
1988	1.09
1989	1.14
1990	1.18
1991	1.23
1992	1.28
1993	1.33
1994	1.39
1995	1.45
1996	1.52
1997	1.6
1998	1.67
1999	1.74
2000	1.82
2001	1.89
2002	1.97
2003	2.04
2004	2.12
2005	2.19
2006	2.27
2007	2.35
2008	2.43
2009	2.5
2010	2.58
2011	2.66
2012	2.74
2013	2.83
2014	2.91
2015	2.99