Year	Percent
1960	0.69583
1961	0.84945
1962	1.09698
1963	1.10319
1964	1.2337
1965	1.40145
1966	1.10115
1967	5.8082
1968	9.15914
1969	10.31696
1970	5.27925
1971	4.39212
1972	5.39027
1973	5.47847
1974	4.34401
1975	8.12407
1976	5.7914
1977	6.02412
1978	5.32605
1979	4.32233
1980	3.2956
1981	2.77007
1982	2.2672
1983	2.21984
1984	1.55679
1985	1.43679
1986	1.31155
1987	0.76979
1988	0.88435
1989	0.57989
1990	0.83312
1991	0.77369
1992	0.56401
1993	0.93322
1994	0.78145
1995	0.48356
1996	0.40618
1997	0.43584
1998	0.54831
1999	0.85542
2000	0.79473
2001	1.29283
2002	1.51718
2003	0.86831
2004	0.72854
2005	0.60064
2006	0.53369
2007	0.58355
2008	0.77646
2009	0.8877
2010	0.53923
2011	0.57923
2012	0.50254
2013	0.4697
2014	0.41472
2015	0.41764
2016	0.43295
2017	0.41171