Year	Years
1970	1.17
1971	1.21
1972	1.24
1973	1.28
1974	1.32
1975	1.36
1976	1.4
1977	1.44
1978	1.48
1979	1.53
1980	1.58
1981	1.62
1982	1.67
1983	1.72
1984	1.78
1985	1.83
1986	1.89
1987	1.95
1988	2.01
1989	2.07
1990	2.13
1991	2.2
1992	2.27
1993	2.34
1994	2.42
1995	2.5
1996	2.57
1997	2.65
1998	2.72
1999	2.8
2000	2.87
2001	2.95
2002	3.03
2003	3.11
2004	3.19
2005	3.27
2006	3.35
2007	3.43
2008	3.52
2009	3.6
2010	3.69
2011	3.78
2012	3.86
2013	3.95
2014	4.05
2015	4.14