Year	Years
1970	1.21
1971	1.24
1972	1.27
1973	1.31
1974	1.35
1975	1.38
1976	1.42
1977	1.46
1978	1.5
1979	1.55
1980	1.59
1981	1.63
1982	1.68
1983	1.73
1984	1.77
1985	1.82
1986	1.87
1987	1.93
1988	1.98
1989	2.04
1990	2.09
1991	2.15
1992	2.21
1993	2.28
1994	2.34
1995	2.41
1996	2.48
1997	2.55
1998	2.62
1999	2.69
2000	2.76
2001	2.83
2002	2.91
2003	2.98
2004	3.06
2005	3.14
2006	3.22
2007	3.3
2008	3.38
2009	3.46
2010	3.55
2011	3.63
2012	3.72
2013	3.8
2014	3.89
2015	3.98