Year	Years
1970	0.84
1971	0.86
1972	0.88
1973	0.91
1974	0.94
1975	0.96
1976	0.99
1977	1.02
1978	1.05
1979	1.08
1980	1.11
1981	1.14
1982	1.17
1983	1.21
1984	1.24
1985	1.28
1986	1.31
1987	1.35
1988	1.39
1989	1.43
1990	1.47
1991	1.51
1992	1.56
1993	1.6
1994	1.65
1995	1.7
1996	1.75
1997	1.8
1998	1.85
1999	1.9
2000	1.96
2001	2.01
2002	2.06
2003	2.12
2004	2.18
2005	2.24
2006	2.29
2007	2.35
2008	2.41
2009	2.48
2010	2.54
2011	2.6
2012	2.67
2013	2.74
2014	2.8
2015	2.87