Year	% of total
1970	12.295634326842485
1971	12.205342236860655
1972	12.331593515828839
1973	12.187285771168186
1974	11.718938706840655
1975	11.162875580530635
1976	11.213257843717662
1977	10.664059407254364
1978	11.217241177665976
1979	10.486577443071042
1980	9.689682739636368
1981	9.70506881010808
1982	7.375455555067657
1983	7.2482352773164935
1984	14.167714637302986
1985	14.505878323504232
1986	13.904884203898677
1987	13.411468719348532
1988	14.189540689277417
1989	14.325065798817224
1990	6.5420560747663545
1991	6.306306306306306
1992	5.128205128205128
1993	4.310344827586207
1994	4.424778761061947
1995	3.4782608695652173
1996	4.504504504504505
1997	4.587155963302752
1998	5.454545454545454
1999	5.405405405405405
2000	6.25
2001	5.3097345132743365
2002	5.3097345132743365
2003	5.128205128205128
2004	5.405405405405405
2005	5.5045871559633035
2006	6.896551724137931
2007	7.228915662650602
2008	7.228915662650602