Year	% of total
1971	100
1972	96.26865671641791
1973	96.96969696969697
1974	48.18652849740933
1975	43.47826086956522
1976	50.609756097560975
1977	32.05417607223476
1978	32.11009174311927
1979	40.38461538461539
1980	50.943396226415096
1981	30.756302521008404
1982	26.986506746626688
1983	24.96570644718793
1984	23.270440251572328
1985	22.531939605110338
1986	21.95945945945946
1987	22.011173184357542
1988	22.087912087912088
1989	11.415525114155251
1990	11.247443762781186
1991	10.558375634517766
1992	10.372608257804632
1993	10.91091091091091
1994	6.660412757973734
1995	7.6382791922739255
1996	15.980230642504118
1997	15.684713375796179
1998	20.253164556962027
1999	18.373493975903614
2000	20.53231939163498
2001	14.78322672352523
2002	14.979757085020243
2003	18.252933507170795
2004	20.714285714285715
2005	27.19186785260483
2006	22.942942942942942
2007	33.852364475201846
2008	23.27113062568606
2009	13.26419213973799
2010	10.645994832041342
2011	11.513963743263107
2012	13.724584103512013
2013	14.74236641221374
2014	12.562562562562562
2015	10.206961429915335