Year	Years
1970	0.95
1971	0.98
1972	1.01
1973	1.03
1974	1.06
1975	1.09
1976	1.12
1977	1.15
1978	1.18
1979	1.21
1980	1.25
1981	1.28
1982	1.32
1983	1.35
1984	1.39
1985	1.43
1986	1.46
1987	1.5
1988	1.54
1989	1.59
1990	1.63
1991	1.67
1992	1.72
1993	1.76
1994	1.81
1995	1.86
1996	1.91
1997	1.96
1998	2.01
1999	2.06
2000	2.12
2001	2.17
2002	2.23
2003	2.29
2004	2.34
2005	2.4
2006	2.46
2007	2.53
2008	2.59
2009	2.65
2010	2.72
2011	2.79
2012	2.86
2013	2.93
2014	3
2015	3.07