Year	Years
1970	0.86
1971	0.89
1972	0.92
1973	0.95
1974	0.98
1975	1.01
1976	1.04
1977	1.07
1978	1.11
1979	1.14
1980	1.18
1981	1.22
1982	1.26
1983	1.3
1984	1.34
1985	1.38
1986	1.43
1987	1.47
1988	1.52
1989	1.57
1990	1.62
1991	1.67
1992	1.72
1993	1.77
1994	1.83
1995	1.89
1996	1.95
1997	2.01
1998	2.07
1999	2.14
2000	2.2
2001	2.27
2002	2.34
2003	2.41
2004	2.48
2005	2.56
2006	2.64
2007	2.72
2008	2.8
2009	2.88
2010	2.96
2011	3.05
2012	3.14
2013	3.23
2014	3.32
2015	3.42