Year	Percent
1961	3.39707
1962	4.67284
1963	6.41425
1964	4.1469
1965	2.73459
1966	2.89359
1967	3.18156
1968	4.24945
1969	6.57253
1970	6.86125
1971	5.87124
1972	6.77411
1973	7.89421
1974	11.84268
1975	13.77669
1976	10.79434
1977	8.78877
1978	9.27882
1979	10.30057
1980	11.67655
1981	11.68233
1982	12.09134
1983	9.63363
1984	7.05619
1985	5.45328
1986	5.04084
1987	2.44046
1988	3.20245
1989	3.27597
1990	2.66706
1991	2.55629
1992	1.96673
1993	1.60713
1994	0.93771
1995	1.14613
1996	1.38306
1997	0.87718
1998	0.9819
1999	0.21764
2000	1.60071
2001	2.03762
2002	2.08466
2003	1.86303
2004	1.66551
2005	1.99203
2006	2.22954
2007	2.61999
2008	2.42802
2009	0.13676
2010	1.05362
2011	1.06017
2012	1.29354
2013	0.77819
2014	0.58551
2015	1.18373
2016	0.181
2017	0.99556