Year	Percent
1970	0.69546
1971	0.84961
1972	1.29966
1973	1.31605
1974	0.51426
1975	0.29309
1976	0.30968
1977	0.46644
1978	0.23164
1979	0.05115
1980	0.21114
1981	0.44742
1982	0.07655
1983	0.25258
1984	0.30705
1985	0.40846
1986	0.42073
1987	0.5473
1988	0.53356
1989	0.32156
1990	0.25599
1991	0.51177
1992	0.77869
1993	0.7964
1994	0.51166
1995	1.34568
1996	1.27058
1997	1.4241
1998	1.49803
1999	3.54126
2000	6.08096
2001	1.35518
2002	1.3071
2003	2.61853
2004	2.17572
2005	3.38221
2006	9.34974
2007	4.92321
2008	4.76009
2009	2.22106
2010	2.9899
2011	3.30736
2012	3.50463
2013	4.04877
2014	1.96127
2015	3.79018
2016	3.77281
2017	5.17853