Year	Years
1970	1.19
1971	1.23
1972	1.28
1973	1.32
1974	1.37
1975	1.41
1976	1.46
1977	1.52
1978	1.57
1979	1.63
1980	1.69
1981	1.75
1982	1.82
1983	1.89
1984	1.96
1985	2.04
1986	2.13
1987	2.21
1988	2.31
1989	2.41
1990	2.51
1991	2.62
1992	2.74
1993	2.87
1994	3
1995	3.14
1996	3.26
1997	3.37
1998	3.49
1999	3.6
2000	3.71
2001	3.83
2002	3.94
2003	4.06
2004	4.17
2005	4.29
2006	4.41
2007	4.52
2008	4.64
2009	4.76
2010	4.88
2011	4.99
2012	5.11
2013	5.23
2014	5.35
2015	5.47