Year	Percent
1960	-0.41775
1961	9.01846
1962	4.62312
1963	-4.39801
1964	-0.50725
1965	0.87015
1966	7.66235
1967	10.32228
1968	12.91903
1969	13.55004
1970	10.84729
1971	6.94069
1972	0.79987
1973	0.12449
1974	37.12232
1975	-10.28727
1976	0.77757
1977	-10.99378
1978	-12.90322
1979	-26.23321
1980	-5.28946
1981	-6.7304
1982	-8.51852
1983	-1.26799
1984	-2.10325
1985	-8.70073
1986	-11.70387
1987	-9.37666
1988	-8.93624
1989	-9.1728
1990	-11.86137
1991	-8.0908
1992	-9.21711
1993	-7.71072
1994	-3.70593
1995	-4.97264
1996	-10.85835
1997	-15.83053
1998	-13.61514
1999	-10.14015
2000	-13.22227
2001	-14.6829
2002	-12.55863
2003	-15.74788
2004	-19.30464
2005	-18.6107
2006	-17.91595
2007	-16.57203
2008	-16.4426
2009	-15.60648
2010	-17.14513
2011	-16.89541
2012	-13.83395
2013	-19.6161
2014	-18.42148
2015	-25.38627
2016	-19.98067
2017	-19.03484