Year	Years
1970	1.19
1971	1.22
1972	1.26
1973	1.3
1974	1.34
1975	1.39
1976	1.43
1977	1.48
1978	1.52
1979	1.57
1980	1.62
1981	1.68
1982	1.73
1983	1.79
1984	1.85
1985	1.91
1986	1.98
1987	2.04
1988	2.11
1989	2.19
1990	2.26
1991	2.34
1992	2.42
1993	2.51
1994	2.59
1995	2.68
1996	2.77
1997	2.86
1998	2.95
1999	3.04
2000	3.13
2001	3.22
2002	3.31
2003	3.4
2004	3.5
2005	3.59
2006	3.69
2007	3.78
2008	3.88
2009	3.98
2010	4.07
2011	4.17
2012	4.27
2013	4.37
2014	4.47
2015	4.57