Year	Years
1970	0.99
1971	1.03
1972	1.06
1973	1.1
1974	1.13
1975	1.17
1976	1.21
1977	1.25
1978	1.29
1979	1.34
1980	1.38
1981	1.43
1982	1.47
1983	1.52
1984	1.57
1985	1.62
1986	1.68
1987	1.73
1988	1.79
1989	1.85
1990	1.91
1991	1.97
1992	2.03
1993	2.1
1994	2.17
1995	2.23
1996	2.31
1997	2.38
1998	2.46
1999	2.54
2000	2.62
2001	2.7
2002	2.79
2003	2.87
2004	2.96
2005	3.05
2006	3.14
2007	3.24
2008	3.33
2009	3.43
2010	3.53
2011	3.63
2012	3.73
2013	3.84
2014	3.94
2015	4.05