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	1.61
1979	1.65
1980	1.7
1981	1.75
1982	1.79
1983	1.84
1984	1.89
1985	1.95
1986	2
1987	2.05
1988	2.11
1989	2.17
1990	2.23
1991	2.29
1992	2.35
1993	2.42
1994	2.48
1995	2.55
1996	2.62
1997	2.69
1998	2.77
1999	2.84
2000	2.92
2001	3
2002	3.08
2003	3.15
2004	3.24
2005	3.32
2006	3.4
2007	3.48
2008	3.57
2009	3.66
2010	3.74
2011	3.83
2012	3.92
2013	4.01
2014	4.11
2015	4.2