Year	% of total
1971	49.32432432432432
1972	44.51219512195122
1973	47.593582887700535
1974	69.23076923076923
1975	67.41071428571429
1976	70.37037037037037
1977	74.02597402597402
1978	81.26984126984127
1979	76.05633802816901
1980	69.01408450704226
1981	74.86187845303867
1982	62.25895316804407
1983	81.94070080862534
1984	73.94736842105263
1985	44.38775510204081
1986	48.51936218678816
1987	50.10266940451745
1988	62.54545454545455
1989	53.82003395585738
1990	62.69230769230769
1991	63.59393232205367
1992	61.82795698924731
1993	67.13852376137513
1994	72.32824427480917
1995	68.61063464837049
1996	73.2128829536528
1997	73.409578270193
1998	66.31989596879063
1999	67.3186119873817
2000	49.9437570303712
2001	46.93877551020408
2002	46.46153846153846
2003	48.84726224783862
2004	50.94688221709007
2005	48.151408450704224
2006	43.787234042553195
2007	37.281947261663284
2008	32.61634728197106
2009	36.980985642219636
2010	37.00260319821495
2011	39.21640424752838
2012	38.18376832320343
2013	37.36149584487535
2014	36.806264896152534
2015	37.83783783783784