Year	% of total
1970	3.31784717384291
1971	3.1456812639404177
1972	3.3514944352651033
1973	3.3118929220516957
1974	3.70086397610457
1975	4.132446531238513
1976	4.8918723757401175
1977	5.141184620992036
1978	5.4714107427585565
1979	4.933776713171001
1980	8.092870990160575
1981	11.50532207588378
1982	10.259560580633686
1983	9.132409595369586
1984	8.195678943178132
1985	8.13480030167713
1986	5.466702973758502
1987	4.992390599829126
1988	4.568460901424359
1989	4.665576070431693
1990	12.76595744680851
1991	12.068965517241379
1992	10.9375
1993	10.9375
1994	13.793103448275861
1995	13.114754098360656
1996	11.864406779661017
1997	11.666666666666666
1998	11.864406779661017
1999	11.864406779661017
2000	13.20754716981132
2001	12.727272727272727
2002	13.793103448275861
2003	15
2004	13.043478260869565
2005	13.513513513513514
2006	10.416666666666668
2007	8.620689655172415
2008	8.771929824561402