Year	Years
1970	0.29
1971	0.3
1972	0.31
1973	0.33
1974	0.34
1975	0.35
1976	0.36
1977	0.37
1978	0.39
1979	0.4
1980	0.42
1981	0.43
1982	0.45
1983	0.46
1984	0.48
1985	0.5
1986	0.51
1987	0.53
1988	0.55
1989	0.57
1990	0.59
1991	0.62
1992	0.64
1993	0.66
1994	0.69
1995	0.71
1996	0.74
1997	0.77
1998	0.8
1999	0.83
2000	0.86
2001	0.89
2002	0.92
2003	0.96
2004	0.99
2005	1.03
2006	1.06
2007	1.1
2008	1.14
2009	1.18
2010	1.22
2011	1.26
2012	1.3
2013	1.35
2014	1.39
2015	1.44