Year	Years
1970	1.16
1971	1.2
1972	1.24
1973	1.28
1974	1.32
1975	1.37
1976	1.41
1977	1.46
1978	1.51
1979	1.56
1980	1.61
1981	1.67
1982	1.72
1983	1.78
1984	1.84
1985	1.9
1986	1.97
1987	2.03
1988	2.1
1989	2.17
1990	2.25
1991	2.32
1992	2.4
1993	2.48
1994	2.57
1995	2.66
1996	2.75
1997	2.85
1998	2.95
1999	3.05
2000	3.16
2001	3.26
2002	3.37
2003	3.48
2004	3.6
2005	3.71
2006	3.83
2007	3.95
2008	4.07
2009	4.19
2010	4.31
2011	4.44
2012	4.56
2013	4.69
2014	4.81
2015	4.94