Year	Years
1970	0.91
1971	0.94
1972	0.97
1973	1
1974	1.03
1975	1.06
1976	1.1
1977	1.13
1978	1.17
1979	1.2
1980	1.24
1981	1.28
1982	1.32
1983	1.36
1984	1.41
1985	1.45
1986	1.5
1987	1.55
1988	1.6
1989	1.65
1990	1.71
1991	1.76
1992	1.82
1993	1.88
1994	1.95
1995	2.01
1996	2.08
1997	2.14
1998	2.21
1999	2.27
2000	2.34
2001	2.41
2002	2.47
2003	2.54
2004	2.61
2005	2.68
2006	2.75
2007	2.83
2008	2.9
2009	2.97
2010	3.05
2011	3.13
2012	3.2
2013	3.28
2014	3.36
2015	3.44