Year	% of total
1960	83.9368217470721
1961	76.53989845770668
1962	70.17245142981882
1963	81.62721550758775
1964	69.92481203007519
1965	62.05711763964191
1966	72.3426842538284
1967	55.78618210469296
1968	53.23612232869834
1969	58.81120762549005
1970	49.32596842086567
1971	51.661930664934644
1972	52.22557608775675
1973	38.213058419243985
1974	38.173734951795794
1975	31.74864186703696
1976	23.454535268082246
1977	42.75372482171563
1978	40.95209995116393
1979	44.31296142421898
1980	27.053998132312817
1981	19.947998109022148
1982	23.197892622416436
1983	23.442077345767824
1984	26.657409445752123
1985	24.906660722672886
1986	20.661633964500734
1987	20.649895178197063
1988	25.43295041274606
1989	13.144701086956523
1990	16.84456965993413
1991	17.605929602129898
1992	12.071474154435228
1993	15.710342964120974
1994	17.548569936980275
1995	13.937534723060944
1996	22.94926888356935
1997	18.373540156597777
1998	17.575184082071647
1999	11.087899648751197
2000	12.790092385966023
2001	17.543453170118465
2002	8.84639271081249
2003	15.732978901182607
2004	11.235776354409149
2005	6.354575135172485
2006	8.782334512927038
2007	9.047538588452785
2008	7.5130716642334825
2009	9.048922633099096
2010	14.180745508179138
2011	10.494866790380506
2012	6.989474113940846
2013	13.098473946952335
2014	14.245914696907427
2015	10.129881350074877