Year	% of total
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0.11560693641618498
1988	2.9180695847362514
1989	3.1487513572204127
1990	2.328042328042328
1991	1.7543859649122806
1992	0.9505703422053232
1993	4.725168756027001
1994	6.4485981308411215
1995	15.81272084805654
1996	13.715710723192021
1997	7.048799380325329
1998	5.760709010339734
1999	1.6452074391988556
2000	0.18703241895261846
2001	0
2002	0.684931506849315
2003	2.3743016759776534
2004	2.6943462897526502
2005	2.5550314465408808
2006	2.050020500205002
2007	1.7319277108433735
2008	1.7253774263120056
2009	1.7144856543037088
2010	2.7308192457737324
2011	2.0311012377023165
2012	4.057971014492753
2013	4.184217916315642
2014	4.172274562584119
2015	4.171934260429835