Year	Percent
1960	0.83083
1961	0.80269
1962	0.6516
1963	0.64738
1964	0.64309
1965	0.59261
1966	0.96151
1967	1.64543
1968	1.35045
1969	1.05158
1970	1.19852
1971	1.03739
1972	0.95522
1973	0.85664
1974	0.92559
1975	1.24829
1976	1.20459
1977	0.94424
1978	0.89398
1979	0.63133
1980	0.68646
1981	0.77262
1982	0.44611
1983	0.32547
1984	0.29683
1985	0.43816
1986	0.4553
1987	0.39364
1988	0.4705
1989	0.44915
1990	0.17418
1991	-0.86869
1992	-0.90346
1993	-0.13611
1994	-0.14538
1995	-0.20232
1996	-0.28813
1997	-0.2879
1998	-0.20698
1999	-0.15698
2000	-0.12944
2001	-1.39543
2002	-1.83065
2003	-0.72126
2004	-0.56979
2005	-0.61753
2006	-0.5924
2007	-1.47722
2008	-1.66638
2009	-0.83309
2010	-0.59396
2011	-0.49187
2012	-0.44518
2013	-0.37132
2014	-0.37458
2015	-0.47073
2016	-0.57265
2017	-0.58945