Year	% of total
1960	29.680418361417782
1961	17.258834765998092
1962	11.527203856749312
1963	19.035940803382665
1964	21.811054488435907
1965	20.91235632183908
1966	20.131015369110607
1967	19.200477326968972
1968	23.847706627789616
1969	33.37504379598579
1970	30.353326360783957
1971	27.950740279507404
1972	30.049345633984125
1973	28.07064592751513
1974	30.98331584090333
1975	31.660998815482788
1976	39.70603315672535
1977	32.37657864523536
1978	44.7470054852793
1979	39.443977269831564
1980	42.633813532284584
1981	21.748270551712338
1982	20.867030965391624
1983	21.515747564992772
1984	24.65829045863051
1985	31.289725641644537
1986	29.94154183412495
1987	30.624321186472415
1988	31.025650543821225
1989	30.882434918334354
1990	18.460010666274343
1991	17.62494395198841
1992	14.10827197921178
1993	17.11717611617741
1994	22.265392878365407
1995	18.19473725306473
1996	22.36028426044715
1997	19.039840407077598
1998	12.249347984095088
1999	13.851735606202398
2000	13.107351091802904
2001	15.115592191821282
2002	17.804015742779
2003	23.647510850745913
2004	19.960393732890676
2005	10.182482785979428
2006	20.757605209446982
2007	18.0195704351037
2008	11.883975617315839
2009	16.08874828289556
2010	18.755732949897116
2011	14.020217412007998
2012	10.783826390762808
2013	15.717754045216612
2014	12.359385555261843
2015	8.303570126973483