Year	% of total
1960	4.30686406460296
1961	5.006364022061943
1962	4.0823832291283555
1963	3.1171623074166965
1964	2.7503736920777277
1965	2.4823781795893347
1966	2.8492392807745506
1967	3.088077336197637
1968	2.907711757269279
1969	4.888569374550683
1970	2.618556701030928
1971	2.5807722616233257
1972	2.3809523809523814
1973	2.9510022271714926
1974	2.7467811158798283
1975	3.25542570951586
1976	2.1241830065359473
1977	2.403770620581304
1978	2.1224489795918364
1979	2.3542970036219955
1980	2.1739130434782603
1981	2.2364217252396164
1982	2.509682416731216
1983	2.3489331181638873
1984	1.8429913166755272
1985	3.6083442961849275
1986	3.0379321920107416
1987	2.332527378751245
1988	3.8849131006280126
1989	3.156480859637341
1990	2.6307125545322347
1991	4.901711392405063
1992	5.068931851135814
1993	7.337404828226555
1994	5.575939177101968
1995	5.4860629921259845
1996	4.745684931506849
1997	4.526350626118068
1998	5.506006006006006
1999	4.895266990291263
2000	6.939310587407668
2001	7.818110773899847
2002	10.155793103448275
2003	10.276855976243503
2004	10.391785942492012
2005	10.913272727272728
2006	9.238291505791505
2007	10.578504837291117
2008	8.796615663900415
2009	7.337519193857965
2010	7.250311608514373
2011	6.446311239193084
2012	5.996685962373372
2013	6.812681744749597
2014	5.777208861957963
2015	5.743740245261984
2016	5.688942154608172