Year	Years
1970	1.12
1971	1.15
1972	1.19
1973	1.23
1974	1.27
1975	1.31
1976	1.35
1977	1.39
1978	1.44
1979	1.48
1980	1.53
1981	1.57
1982	1.62
1983	1.67
1984	1.73
1985	1.78
1986	1.83
1987	1.89
1988	1.95
1989	2
1990	2.06
1991	2.13
1992	2.19
1993	2.25
1994	2.32
1995	2.39
1996	2.46
1997	2.53
1998	2.61
1999	2.68
2000	2.76
2001	2.84
2002	2.92
2003	3.01
2004	3.1
2005	3.19
2006	3.28
2007	3.37
2008	3.47
2009	3.56
2010	3.66
2011	3.77
2012	3.87
2013	3.98
2014	4.09
2015	4.2