Year	% of total
1971	30.96960926193922
1972	28.440366972477065
1973	29.84165651644336
1974	32.860520094562645
1975	42.02453987730061
1976	41.48351648351649
1977	39.79848866498741
1978	40.78841512469831
1979	42.53731343283582
1980	46.4694014794889
1981	38.35125448028674
1982	40.27061855670103
1983	40.71641791044776
1984	46.507936507936506
1985	52.666352052855125
1986	53.585746102449896
1987	55.86206896551724
1988	57.99640610961365
1989	50.280673616680026
1990	51.85633575464084
1991	53.6794919686216
1992	49.3324432576769
1993	49.63072378138848
1994	55.09181969949917
1995	59.95067817509248
1996	58.149556400506974
1997	62.069741282339706
1998	77.07175646291374
1999	77.6244880362147
2000	63.03243454474404
2001	61.14310087438686
2002	58.346487766377265
2003	61.75115207373272
2004	57.068996256017115
2005	50.18284574468085
2006	46.057754704737185
2007	43.44428817002657
2008	38.523104802174565
2009	24.52613440551407
2010	32.3213575500464
2011	23.81434941224159
2012	27.636973537085353
2013	27.957867232791706
2014	37.63509218054673
2015	41.145898559799626