Year	Years
1970	1.14
1971	1.17
1972	1.2
1973	1.23
1974	1.27
1975	1.3
1976	1.34
1977	1.37
1978	1.41
1979	1.45
1980	1.49
1981	1.53
1982	1.57
1983	1.61
1984	1.65
1985	1.69
1986	1.74
1987	1.79
1988	1.83
1989	1.88
1990	1.93
1991	1.98
1992	2.04
1993	2.09
1994	2.14
1995	2.2
1996	2.26
1997	2.32
1998	2.38
1999	2.44
2000	2.51
2001	2.57
2002	2.64
2003	2.7
2004	2.77
2005	2.84
2006	2.91
2007	2.99
2008	3.06
2009	3.13
2010	3.21
2011	3.29
2012	3.37
2013	3.45
2014	3.53
2015	3.61