Year	Years
1970	1.3
1971	1.34
1972	1.38
1973	1.43
1974	1.47
1975	1.52
1976	1.57
1977	1.62
1978	1.67
1979	1.73
1980	1.78
1981	1.84
1982	1.9
1983	1.96
1984	2.03
1985	2.1
1986	2.17
1987	2.25
1988	2.32
1989	2.41
1990	2.49
1991	2.58
1992	2.67
1993	2.77
1994	2.88
1995	2.99
1996	3.11
1997	3.24
1998	3.36
1999	3.48
2000	3.61
2001	3.73
2002	3.86
2003	3.98
2004	4.11
2005	4.23
2006	4.35
2007	4.48
2008	4.6
2009	4.73
2010	4.85
2011	4.98
2012	5.1
2013	5.22
2014	5.35
2015	5.47