Year	Percent
1960	0.97739
1961	0.88913
1962	0.97109
1963	1.01619
1964	1.02577
1965	1.00123
1966	0.99959
1967	1.01993
1968	1.00684
1969	0.96163
1970	0.8855
1971	0.83254
1972	0.8019
1973	0.74058
1974	0.6494
1975	0.52895
1976	0.46863
1977	0.55102
1978	0.65305
1979	0.61751
1980	0.61372
1981	0.6924
1982	0.67741
1983	0.68301
1984	0.67838
1985	0.65376
1986	0.67939
1987	0.67481
1988	0.28641
1989	0.29542
1990	0.18665
1991	0.04906
1992	0.21558
1993	0.22488
1994	-0.11727
1995	-0.3232
1996	-0.33409
1997	-0.42413
1998	-0.47558
1999	-0.42061
2000	-0.47113
2001	-0.51297
2002	-0.63657
2003	-0.69981
2004	-0.68217
2005	-0.68301
2006	-0.6123
2007	-0.45885
2008	-0.34542
2009	-0.22296
2010	-0.17036
2011	-0.18362
2012	-0.09164
2013	0.01587
2014	0.0899
2015	0.1593
2016	0.12551
2017	0.06671