Year	% of total
1971	9.040451484101945
1972	11.422478965821728
1973	11.45027192069896
1974	11.580913848774523
1975	12.308392531751636
1976	7.695408166227252
1977	8.929074901159177
1978	9.820178180139367
1979	9.725734543533797
1980	9.697903959188201
1981	7.2917846983535926
1982	8.537323903332952
1983	8.283183918019112
1984	8.485301614273578
1985	10.151659726291662
1986	8.71648235359086
1987	7.5216146907061425
1988	7.277810087928886
1989	5.457824395735391
1990	4.838998022650732
1991	3.854705080911099
1992	3.931284680233063
1993	3.835510654259075
1994	3.8655594230514927
1995	3.7808806570548392
1996	13.33205008213273
1997	17.3218748641596
1998	17.330495480863803
1999	21.0072842277264
2000	25.4861878174381
2001	27.465277020278435
2002	29.64712259191763
2003	32.077444301171916
2004	32.822379396949614
2005	31.049760231426195
2006	36.32541118577215
2007	39.669250336525806
2008	39.07586139141308
2009	39.80167891572764
2010	41.55418573587054
2011	39.430867777456626
2012	36.17277073831082
2013	36.475068805657784
2014	36.724581325344765