Year	% of total
1970	9.946460999842596
1971	10.953647808463161
1972	11.299848200562375
1973	11.2549517252358
1974	12.272557606794377
1975	11.813518795293193
1976	12.431872895631333
1977	12.32278206425378
1978	12.296776619168876
1979	9.747967044838186
1980	10.17915009049794
1981	10.651162000888718
1982	10.55774606115976
1983	10.599078799031798
1984	12.161164351049596
1985	11.451099990045195
1986	12.11155227186592
1987	11.686146329758461
1988	12.468396951074356
1989	13.498894171843965
1990	9.375
1991	8.16326530612245
1992	8.421052631578947
1993	8.791208791208792
1994	8.045977011494253
1995	9.090909090909092
1996	8.536585365853659
1997	8.13953488372093
1998	7.777777777777778
1999	7.216494845360824
2000	7.07070707070707
2001	6.666666666666667
2002	6.363636363636363
2003	5.88235294117647
2004	5.511811023622047
2005	5.223880597014925
2006	4.794520547945205
2007	4.545454545454546
2008	4.320987654320987