Year	Percent
1961	2.78216
1962	5.79373
1963	8.45786
1964	6.48981
1965	4.19704
1966	2.2324
1967	2.77526
1968	1.73445
1969	4.05132
1970	10.59306
1971	7.17884
1972	5.63297
1973	12.73863
1974	20.24638
1975	16.98309
1976	17.45428
1977	18.47716
1978	13.94497
1979	15.45103
1980	20.81579
1981	18.78723
1982	17.54095
1983	15.09674
1984	10.76185
1985	9.17464
1986	7.48842
1987	6.00928
1988	6.6504
1989	6.19739
1990	8.91406
1991	7.58133
1992	4.36812
1993	3.88595
1994	3.54247
1995	4.92524
1996	4.55387
1997	2.60198
1998	2.52981
1999	1.62067
2000	1.96532
2001	2.98612
2002	3.3542
2003	3.18133
2004	2.52373
2005	1.88823
2006	1.89885
2007	2.43461
2008	2.48058
2009	1.95783
2010	0.31945
2011	1.46839
2012	1.38015
2013	1.21194
2014	0.95891
2015	0.9379
2016	0.84845
2017	0.62911