Year	% of total
1971	23.639455782312925
1972	32.65895953757225
1973	21.105527638190953
1974	32.43559718969556
1975	39.812889812889814
1976	30.852017937219735
1977	17.860016090104587
1978	11.81046676096181
1979	40.13194062671798
1980	77.3013150371641
1981	91.63135593220339
1982	88.75192604006163
1983	50.38719669592153
1984	24.933155080213904
1985	76.12107623318386
1986	64.21278882321333
1987	48.41233317993557
1988	53.69969710082215
1989	72.42162653339392
1990	66.66666666666666
1991	69.0148596587782
1992	56.648648648648646
1993	50.22851919561243
1994	49.724692926725965
1995	60.536138445877164
1996	54.69613259668509
1997	46.61374348796824
1998	34.236698160119346
1999	36.41270500311397
2000	36.75
2001	36.8474923234391
2002	32.659614658103514
2003	36.01336740711618
2004	31.724137931034484
2005	25.294842457313855
2006	26.702033598585324
2007	31.912626531699523
2008	32.72413793103448
2009	36.29705331289389
2010	27.124895222129087
2011	29.08673553041482
2012	25.498859749144813
2013	20.99346405228758
2014	23.08713492638185
2015	15.520606130180232