Year	% of total
1970	37.624902183526174
1971	38.62806492952101
1972	40.200756387069625
1973	39.81381780484616
1974	38.953688674623166
1975	39.71266536450989
1976	39.126991036422524
1977	38.36398734815632
1978	38.076972510513464
1979	37.812355468980414
1980	37.06597437357052
1981	35.63293483529717
1982	35.95413611133825
1983	35.93290638202972
1984	36.85960930443061
1985	37.61881063825987
1986	36.70600878496717
1987	34.675824257584296
1988	33.77677989425831
1989	32.23991445517038
1990	16.39344262295082
1991	14.166666666666666
1992	12
1993	9.269662921348315
1994	5.811138014527845
1995	3.8834951456310676
1996	4.050632911392405
1997	4.266666666666667
1998	4.143646408839778
1999	4.0650406504065035
2000	4
2001	4.336043360433604
2002	4.670329670329671
2003	4.619565217391304
2004	5.013927576601671
2005	5.307262569832402
2006	5.099150141643059
2007	5.294117647058823
2008	5.263157894736842