Year	% of total
1970	4.261503739949559
1971	4.540061641613496
1972	4.53034827736433
1973	4.143553228728467
1974	5.59504094488189
1975	5.102574619259053
1976	4.947997387316088
1977	4.149308925674255
1978	5.0396242793398285
1979	4.717074451848105
1980	3.6779858447504434
1981	4.7014038782993905
1982	4.009145833147226
1983	4.550808689273554
1984	4.587540333078252
1985	5.114819262014032
1986	5.073856949238686
1987	4.8423412031558195
1988	5.125570263976739
1989	4.68404647645692
1990	10.344827586206897
1991	10.714285714285714
1992	12.264150943396226
1993	12.264150943396226
1994	12.380952380952381
1995	14.000000000000002
1996	12.745098039215685
1997	12.173913043478262
1998	6.299212598425196
1999	10.256410256410255
2000	12.4031007751938
2001	14.285714285714285
2002	12.977099236641221
2003	13.138686131386862
2004	15.32258064516129
2005	11.242603550295858
2006	13.60544217687075
2007	15.789473684210526
2008	15.172413793103448