Year	Percent
1960	0.72276
1961	0.7929
1962	0.59578
1963	0.37089
1964	0.36261
1965	0.46779
1966	0.7378
1967	0.81441
1968	0.65053
1969	0.36542
1970	0.2282
1971	0.43384
1972	0.65004
1973	0.45413
1974	0.36818
1975	0.93866
1976	1.55321
1977	1.30111
1978	1.2966
1979	1.2467
1980	0.98222
1981	0.89662
1982	0.61646
1983	0.58172
1984	0.49816
1985	0.38829
1986	0.33076
1987	0.33436
1988	0.3632
1989	0.52185
1990	1.05781
1991	1.20035
1992	0.76388
1993	0.58826
1994	0.5007
1995	0.4672
1996	0.44067
1997	0.49327
1998	0.55421
1999	0.38347
2000	0.40904
2001	0.51988
2002	0.36657
2003	0.23864
2004	0.24741
2005	0.29325
2006	0.30033
2007	0.25476
2008	0.26546
2009	0.26303
2010	0.12888
2011	-0.14795
2012	-0.54075
2013	-0.72512
2014	-0.66611
2015	-0.65886
2016	-0.41591
2017	-0.14441