Year	Years
1970	1.3
1971	1.33
1972	1.37
1973	1.41
1974	1.45
1975	1.49
1976	1.53
1977	1.57
1978	1.62
1979	1.66
1980	1.71
1981	1.76
1982	1.81
1983	1.86
1984	1.91
1985	1.96
1986	2.02
1987	2.08
1988	2.13
1989	2.19
1990	2.26
1991	2.32
1992	2.39
1993	2.46
1994	2.53
1995	2.6
1996	2.68
1997	2.75
1998	2.83
1999	2.91
2000	2.99
2001	3.07
2002	3.15
2003	3.23
2004	3.32
2005	3.4
2006	3.49
2007	3.58
2008	3.67
2009	3.75
2010	3.85
2011	3.94
2012	4.03
2013	4.12
2014	4.22
2015	4.32