Year	Percent
1960	1.63087
1961	1.60689
1962	1.58431
1963	1.55753
1964	1.52422
1965	1.48954
1966	1.44954
1967	1.42053
1968	1.42479
1969	1.47103
1970	1.54303
1971	1.62761
1972	1.69491
1973	1.72192
1974	1.69542
1975	1.63398
1976	1.5613
1977	1.5047
1978	1.47419
1979	1.48029
1980	1.51052
1981	1.54454
1982	1.5664
1983	1.57663
1984	1.57026
1985	1.55162
1986	1.5298
1987	1.5092
1988	1.48618
1989	1.46131
1990	1.43457
1991	1.40826
1992	1.37995
1993	1.34514
1994	1.30249
1995	1.25575
1996	1.20678
1997	1.16286
1998	1.13111
1999	1.11534
2000	1.11088
2001	1.11114
2002	1.10897
2003	1.10242
2004	1.08861
2005	1.07043
2006	1.05053
2007	1.03443
2008	1.0259
2009	1.02738
2010	1.03504
2011	1.04486
2012	1.05038
2013	1.04728
2014	1.03271
2015	1.00985
2016	0.98474
2017	0.96147