Year	Years
1970	1.32
1971	1.35
1972	1.39
1973	1.42
1974	1.46
1975	1.5
1976	1.54
1977	1.58
1978	1.62
1979	1.66
1980	1.7
1981	1.75
1982	1.79
1983	1.84
1984	1.88
1985	1.93
1986	1.98
1987	2.03
1988	2.08
1989	2.13
1990	2.18
1991	2.24
1992	2.29
1993	2.35
1994	2.41
1995	2.47
1996	2.52
1997	2.58
1998	2.65
1999	2.71
2000	2.77
2001	2.84
2002	2.91
2003	2.98
2004	3.05
2005	3.12
2006	3.19
2007	3.27
2008	3.34
2009	3.42
2010	3.5
2011	3.58
2012	3.66
2013	3.75
2014	3.83
2015	3.92