Year	% of total
1971	12.523719165085389
1972	11.546583326294451
1973	8.661045531197303
1974	11.321651321651322
1975	8.364811133200794
1976	7.738893455033093
1977	5.2394027156128935
1978	5.737860996509045
1979	6.539325842696629
1980	5.327747791294073
1981	6.737632750516079
1982	4.649598812671027
1983	5.574206755373592
1984	4.458444840915849
1985	6.30785939627976
1986	6.290007042804602
1987	7.351565509271997
1988	4.232038166670623
1989	4.896739420460003
1990	6.036765333915404
1991	3.0780098008917927
1992	2.489469791968104
1993	2.9552207501660432
1994	1.4502608738656313
1995	1.52369175053412
1996	1.196416672836307
1997	1.2664667693166571
1998	1.9803858952464262
1999	1.7653101071325488
2000	1.389822754275178
2001	1.3427703574790464
2002	0.9802791961286097
2003	1.4283591352920095
2004	1.1810851799722868
2005	0.9469570015004872
2006	0.8621075397121336
2007	0.8525375377138095
2008	0.6915411230447632
2009	0.6227915585508196
2010	0.7412656678437263
2011	0.8841406548947895
2012	0.7475491350165274
2013	0.7973734455493771
2014	0.5041530338947654
2015	0.390731684224709