Year	% of total
1971	14.804845222072679
1972	20.320197044334975
1973	26.799714896650034
1974	16.19947848761408
1975	9.03581267217631
1976	9.185360094451003
1977	5.802415875754961
1978	4.562043795620438
1979	4.526364909006066
1980	3.608030324301558
1981	4.495210022107591
1982	5.097914005959983
1983	2.2998629868858878
1984	4.042210695761045
1985	5.263157894736842
1986	1.9258916878514751
1987	3.922339254834146
1988	1.3103250751825861
1989	1.4748107543722264
1990	0.8383010432190761
1991	1.689247621793024
1992	1.0882642458711582
1993	1.8182754713093643
1994	0.8348840718201479
1995	0.9789500380421
1996	0.6536264161905684
1997	0.34888589105456574
1998	0.9242541483965265
1999	0.8199701094639901
2000	0.2124980324256257
2001	0.2591549295774648
2002	0.20616319444444445
2003	0.8961482533563289
2004	0.8031999999999999
2005	1.6364440513047325
2006	0.6188610685289275
2007	0.6075922142165824
2008	0.7033502336216324
2009	0.7947845510506221
2010	0.3804609262255652
2011	0.9800093706075277
2012	1.0836803317246546
2013	0.5510101853397896
2014	0.3953799694903646
2015	0.21076194075409171