Year	Years
1970	1.2
1971	1.24
1972	1.28
1973	1.33
1974	1.37
1975	1.42
1976	1.47
1977	1.52
1978	1.57
1979	1.62
1980	1.67
1981	1.73
1982	1.79
1983	1.85
1984	1.91
1985	1.97
1986	2.04
1987	2.11
1988	2.18
1989	2.25
1990	2.32
1991	2.4
1992	2.48
1993	2.57
1994	2.65
1995	2.74
1996	2.84
1997	2.93
1998	3.03
1999	3.13
2000	3.23
2001	3.34
2002	3.44
2003	3.55
2004	3.66
2005	3.77
2006	3.88
2007	3.99
2008	4.11
2009	4.22
2010	4.34
2011	4.46
2012	4.58
2013	4.71
2014	4.83
2015	4.96