Year	% of total
1970	12.80296969657827
1971	12.571131187069254
1972	12.568913545865682
1973	16.33804704591994
1974	14.738563975213209
1975	8.546696870633877
1976	8.122449308932064
1977	8.65391255931858
1978	8.839595665657267
1979	8.057545960379606
1980	7.411857096778715
1981	7.1909287928676
1982	7.406536856871352
1983	8.82310490579675
1984	8.338429903602298
1985	8.312814649460353
1986	8.425642383924473
1987	7.6813979504048575
1988	8.226142238595584
1989	6.703826484123597
1990	8.333333333333332
1991	8.16326530612245
1992	8.16326530612245
1993	8
1994	7.8431372549019605
1995	7.8431372549019605
1996	7.8431372549019605
1997	7.8431372549019605
1998	7.8431372549019605
1999	7.547169811320755
2000	7.547169811320755
2001	7.547169811320755
2002	7.547169811320755
2003	8.928571428571429
2004	9.25925925925926
2005	9.433962264150944
2006	11.363636363636363
2007	11.904761904761903
2008	9.30232558139535