Year	Percent
1960	1.00388
1961	1.10704
1962	1.2867
1963	1.18127
1964	1.379
1965	1.35073
1966	1.34139
1967	1.10254
1968	0.91319
1969	0.81641
1970	0.75488
1971	0.78881
1972	0.81692
1973	0.78248
1974	0.75821
1975	0.96267
1976	0.98622
1977	1.00338
1978	1.02849
1979	1.01688
1980	1.15319
1981	1.21027
1982	1.19227
1983	1.20454
1984	1.15355
1985	0.96027
1986	0.92212
1987	1.0138
1988	1.05318
1989	0.87272
1990	0.87259
1991	0.8981
1992	0.9156
1993	0.78273
1994	0.82081
1995	0.65895
1996	0.64977
1997	0.6795
1998	0.70831
1999	0.63304
2000	0.60287
2001	0.75349
2002	0.64954
2003	0.67207
2004	0.67656
2005	0.65266
2006	0.58269
2007	0.56215
2008	0.42384
2009	0.43405
2010	0.51517
2011	0.42824
2012	0.41904
2013	0.41895
2014	0.42067
2015	0.47791
2016	0.4448
2017	0.50606