Year	% of total
1971	9.581881533101045
1972	12.786108918705605
1973	15.515961395694136
1974	14.509536784741146
1975	14.892227302416721
1976	11.53612629022465
1977	23.46590909090909
1978	22.805194805194805
1979	18.27741612418628
1980	4.31266846361186
1981	2.9598308668076108
1982	2.719155844155844
1983	2.578397212543554
1984	1.728073035539615
1985	1.7755681818181819
1986	1.627670396744659
1987	3.925949569103096
1988	4.290635765737551
1989	2.404692082111437
1990	2.4798154555940024
1991	5.124223602484472
1992	17.162052117263844
1993	10.077361563517915
1994	9.853420195439739
1995	17.250563409137474
1996	9.287796751353602
1997	3.047585100695063
1998	8.147053389987068
1999	2.15280025898349
2000	0.8527243821361469
2001	1.4825796886582654
2002	1.621262458471761
2003	2.1065342814973835
2004	0.8034083992696287
2005	3.280871670702179
2006	6.128550074738415
2007	7.9779005524861875
2008	7.145872915347266
2009	4.844253490870033
2010	6.688928310549932
2011	8.777461350691619
2012	8.15804993119717
2013	11.685393258426966
2014	10.208476069296271
2015	0.9988901220865706