Year	Years
1970	0.86
1971	0.89
1972	0.92
1973	0.96
1974	0.99
1975	1.03
1976	1.07
1977	1.11
1978	1.15
1979	1.19
1980	1.23
1981	1.28
1982	1.32
1983	1.37
1984	1.42
1985	1.47
1986	1.52
1987	1.58
1988	1.63
1989	1.69
1990	1.75
1991	1.81
1992	1.87
1993	1.93
1994	2
1995	2.06
1996	2.14
1997	2.21
1998	2.29
1999	2.37
2000	2.45
2001	2.53
2002	2.61
2003	2.7
2004	2.78
2005	2.87
2006	2.96
2007	3.05
2008	3.14
2009	3.24
2010	3.33
2011	3.43
2012	3.52
2013	3.62
2014	3.71
2015	3.81