Year	Years
1970	1.24
1971	1.28
1972	1.32
1973	1.35
1974	1.39
1975	1.43
1976	1.48
1977	1.52
1978	1.56
1979	1.61
1980	1.65
1981	1.7
1982	1.75
1983	1.8
1984	1.85
1985	1.91
1986	1.96
1987	2.02
1988	2.08
1989	2.14
1990	2.2
1991	2.26
1992	2.33
1993	2.4
1994	2.46
1995	2.53
1996	2.6
1997	2.67
1998	2.74
1999	2.81
2000	2.89
2001	2.96
2002	3.03
2003	3.11
2004	3.19
2005	3.27
2006	3.35
2007	3.43
2008	3.51
2009	3.59
2010	3.67
2011	3.76
2012	3.84
2013	3.93
2014	4.02
2015	4.11