Year	Percent
1966	-7.40671
1967	-6.66838
1968	-11.00292
1969	-10.69883
1970	-3.1173
1971	-4.81406
1972	-6.98269
1973	-7.27844
1974	-4.74246
1975	1.09397
1976	-5.29804
1977	-10.78162
1978	-26.20675
1979	-28.29566
1980	-20.86226
1981	-22.79594
1982	-15.30377
1983	-11.99396
1984	-13.66425
1985	-10.05177
1986	-9.47417
1987	-9.86882
1988	-8.08757
1989	-10.21744
1990	-11.67994
1991	-5.22511
1992	-6.25767
1993	-8.24589
1994	-7.43684
1995	-11.7255
1996	-7.35705
1997	-2.45309
1998	-3.25981
1999	-3.61858
2000	-4.76247
2001	-3.28767
2002	-5.32818
2003	-6.67122
2004	-14.53311
2005	-16.81431
2006	-13.36416
2007	-13.18001
2008	-16.39528
2009	-16.5604
2010	-18.93331
2011	-14.60797
2012	-13.42537
2013	-11.7405
2014	-19.29027
2015	-25.72251
2016	-18.95532
2017	-19.16513