Year	% of total
1960	30.973451327433633
1961	35.82089552238806
1962	43.08510638297872
1963	37.30569948186528
1964	35.80786026200873
1965	37.81818181818182
1966	39.261744966442954
1967	31.14285714285714
1968	27.245508982035926
1969	38.52140077821012
1970	26.096491228070175
1971	18.95551257253385
1972	12.440191387559809
1973	19.015659955257274
1974	15.86998087954111
1975	18.79310344827586
1976	21.402214022140225
1977	18.865030674846626
1978	26.6553480475382
1979	15.711947626841244
1980	17.916666666666668
1981	16.820702402957487
1982	18.324607329842934
1983	15.261627906976743
1984	13.860103626943006
1985	11.389759665621733
1986	13.53558926487748
1987	14.2018779342723
1988	12.78772378516624
1989	12.15323645970938
1990	9.41527027027027
1991	9.100583941605839
1992	1.5386013986013984
1993	1.3481617647058823
1994	1.1283076923076922
1995	1.1734399999999998
1996	0.6215254237288135
1997	0.3333636363636363
1998	0.34923809523809524
1999	0.44719512195121947
2000	0.47623376623376623
2001	8.601604938271604
2002	5.000454545454545
2003	6.79074074074074
2004	8.11283185840708
2005	6.484329268292684
2006	8.316907216494846
2007	31.697796610169494
2008	24.558041002277903
2009	25.60788333333333
2010	26.519134948096884
2011	35.114665579119084
2012	35.090909090909086
2013	46.322267920094006
2014	56.061434058898854
2015	49.75003754693366
2016	65.35100135317997