Year	Percent
1961	3.39357
1962	0.58747
1963	1.95055
1964	1.7701
1965	-0.86736
1966	1.19638
1967	2.2778
1968	2.07561
1969	4.48295
1970	7.31747
1971	2.44355
1972	6.41309
1973	14.84042
1974	23.21303
1975	24.54089
1976	16.60178
1977	16.93878
1978	7.90848
1979	9.14997
1980	18.82958
1981	41.10215
1982	84.17189
1983	62.92585
1984	17.88361
1985	17.18355
1986	19.28796
1987	12.23372
1988	20.73305
1989	15.34238
1990	17.11317
1991	26.26193
1992	19.69187
1993	10.37726
1994	15.65799
1995	21.21806
1996	15.25812
1997	14.60561
1998	12.14891
1999	11.40101
2000	9.51862
2001	9.75903
2002	9.861
2003	10.72254
2004	13.44588
2005	13.10309
2006	13.0375
2007	10.53528
2008	11.41769
2009	9.8273
2010	6.57081
2011	4.54839
2012	4.35587
2013	4.01324
2014	5.79755
2015	3.77691
2016	1.78943
2017	1.97831