Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0
1971	0
1972	0
1973	0
1974	1.176215120697767
1975	3.2364067097168623
1976	3.9548795077764485
1977	4.649827784156142
1978	4.743647151013097
1979	4.222409092067375
1980	4.218715488256804
1981	2.4615610256911684
1982	2.341226472374013
1983	1.7821172121240847
1984	1.843796232914523
1985	2.892428996701263
1986	3.7185888848292943
1987	4.007340549043107
1988	4.8851108058948
1989	7.304383373283535
1990	8.560604667414532
1991	8.543441520366985
1992	8.971849285404938
1993	9.093141668986068
1994	9.797199494141488
1995	10.359959397204653
1996	12.269903276490854
1997	9.951428241008442
1998	12.574287058018726
1999	13.730797471817096
2000	14.477820967188752
2001	15.694224418011437
2002	15.509305583350011
2003	16.421981358062755
2004	14.848855495369563
2005	15.911988892352158
2006	14.971085625425212
2007	12.994030401870885
2008	14.24346523401178
2009	13.588366704130763
2010	13.956169273867665
2011	12.848804778166285
2012	9.552484696993368
2013	9.526081648118781
2014	8.107909654301407
2015	7.573217487645232