Year	Years
1970	0.87
1971	0.89
1972	0.91
1973	0.94
1974	0.96
1975	0.99
1976	1.02
1977	1.04
1978	1.07
1979	1.1
1980	1.13
1981	1.16
1982	1.19
1983	1.22
1984	1.26
1985	1.29
1986	1.32
1987	1.36
1988	1.39
1989	1.43
1990	1.47
1991	1.51
1992	1.55
1993	1.59
1994	1.63
1995	1.67
1996	1.71
1997	1.76
1998	1.8
1999	1.85
2000	1.89
2001	1.94
2002	1.99
2003	2.04
2004	2.09
2005	2.15
2006	2.2
2007	2.26
2008	2.31
2009	2.37
2010	2.43
2011	2.49
2012	2.55
2013	2.62
2014	2.68
2015	2.75