Year	Years
1970	1.13
1971	1.16
1972	1.19
1973	1.22
1974	1.26
1975	1.29
1976	1.33
1977	1.37
1978	1.4
1979	1.44
1980	1.48
1981	1.52
1982	1.57
1983	1.61
1984	1.65
1985	1.7
1986	1.75
1987	1.8
1988	1.84
1989	1.9
1990	1.95
1991	2
1992	2.06
1993	2.11
1994	2.17
1995	2.23
1996	2.29
1997	2.35
1998	2.41
1999	2.48
2000	2.54
2001	2.61
2002	2.67
2003	2.74
2004	2.81
2005	2.88
2006	2.95
2007	3.02
2008	3.09
2009	3.17
2010	3.24
2011	3.32
2012	3.39
2013	3.47
2014	3.55
2015	3.63