Year	Percent
1960	2.35294
1961	1.63934
1962	-3.52
1963	-6.71875
1964	-0.61538
1965	-4.83871
1966	-8.7188
1967	-4.90098
1968	-6.39954
1969	-6.67726
1970	-3.72897
1971	-6.65767
1972	-7.97357
1973	-1.84426
1974	-9.17016
1975	-8.52757
1976	-4.81655
1977	-3.39243
1978	-9.01912
1979	-1.70532
1980	-11.94555
1981	-11.92922
1982	-12.59793
1983	-9.17722
1984	-7.03283
1985	-9.10488
1986	-7.5702
1987	-11.69118
1988	-10.98373
1989	-11.1492
1990	-8.45494
1991	-10.73876
1992	-12.69463
1993	-15.32852
1994	-58.49046
1995	-20.67059
1996	-20.16733
1997	-17.87278
1998	-17.62434
1999	-18.28693
2000	-18.55853
2001	-15.81009
2002	-16.66236
2003	-15.08631
2004	-13.63832
2005	-13.78635
2006	-12.80376
2007	-9.55126
2008	-17.28089
2009	-17.94188
2010	-17.95202
2011	-16.60208
2012	-18.99773
2013	-17.83969
2014	-18.18847
2015	-24.06185
2016	-18.17911
2017	-14.53122