Year	Years
1970	1.07
1971	1.1
1972	1.14
1973	1.18
1974	1.21
1975	1.25
1976	1.29
1977	1.34
1978	1.38
1979	1.42
1980	1.47
1981	1.51
1982	1.56
1983	1.61
1984	1.66
1985	1.72
1986	1.77
1987	1.83
1988	1.88
1989	1.94
1990	2.01
1991	2.07
1992	2.13
1993	2.2
1994	2.27
1995	2.34
1996	2.42
1997	2.49
1998	2.57
1999	2.65
2000	2.74
2001	2.82
2002	2.91
2003	3
2004	3.09
2005	3.19
2006	3.28
2007	3.38
2008	3.48
2009	3.58
2010	3.69
2011	3.79
2012	3.9
2013	4.01
2014	4.13
2015	4.24