Year	Years
1970	0.9
1971	0.93
1972	0.96
1973	1
1974	1.03
1975	1.07
1976	1.1
1977	1.14
1978	1.18
1979	1.22
1980	1.26
1981	1.3
1982	1.34
1983	1.39
1984	1.44
1985	1.49
1986	1.54
1987	1.59
1988	1.64
1989	1.7
1990	1.75
1991	1.81
1992	1.87
1993	1.94
1994	2
1995	2.07
1996	2.15
1997	2.23
1998	2.31
1999	2.39
2000	2.47
2001	2.55
2002	2.64
2003	2.73
2004	2.82
2005	2.91
2006	3
2007	3.09
2008	3.19
2009	3.29
2010	3.39
2011	3.49
2012	3.59
2013	3.7
2014	3.81
2015	3.92