Year	Years
1970	1.17
1971	1.2
1972	1.23
1973	1.26
1974	1.3
1975	1.33
1976	1.37
1977	1.4
1978	1.44
1979	1.48
1980	1.52
1981	1.55
1982	1.6
1983	1.64
1984	1.68
1985	1.72
1986	1.77
1987	1.81
1988	1.86
1989	1.91
1990	1.96
1991	2.01
1992	2.06
1993	2.11
1994	2.16
1995	2.22
1996	2.27
1997	2.33
1998	2.39
1999	2.45
2000	2.51
2001	2.57
2002	2.64
2003	2.7
2004	2.77
2005	2.84
2006	2.91
2007	2.98
2008	3.05
2009	3.12
2010	3.2
2011	3.28
2012	3.36
2013	3.44
2014	3.52
2015	3.6