Year	% of total
1971	3.0465444287729198
1972	3.2920652785593694
1973	2.079002079002079
1974	2.3309352517985613
1975	2.473684210526316
1976	1.9569471624266144
1977	1.8115942028985508
1978	1.9607843137254901
1979	3.9680619404790707
1980	4.54443194600675
1981	4.094778007821486
1982	3.578110383536015
1983	3.009961022087484
1984	2.8955532574974145
1985	2.784761168052601
1986	2.719200887902331
1987	2.763865702096086
1988	2.6706231454005933
1989	0.3171399740521839
1990	0.4424778761061947
1991	0.4165877674682825
1992	0.31286020088918165
1993	0.3065825067628494
1994	0.338855421686747
1995	0.291403593977659
1996	0.2946472417744312
1997	0.3767598651596272
1998	0.4018612521150592
1999	0.4523181304183943
2000	0.05015045135406219
2001	0.08386447500838644
2002	0.13114754098360656
2003	0.1138766878151944
2004	0.1132342533616419
2005	0.09492812584757254
2006	0.6098369349065358
2007	1.1037807663029688
2008	1.2849384024374089
2009	1.0949834479246243
2010	1.0879190385831752
2011	1.1140650715280416
2012	0.1182343667892801
2013	0.10898522644708163
2014	0.12443438914027148
2015	0.1789308879445314