Year	% of total
1970	48.37932170916108
1971	48.82684136786948
1972	48.93964924835174
1973	48.01254202091273
1974	50.23006308745106
1975	49.430965040251294
1976	45.077727783528346
1977	46.62463916141994
1978	45.170077057921254
1979	44.65561302454433
1980	45.001164230406744
1981	44.497330934804545
1982	48.01735547037912
1983	47.86576124677894
1984	49.183506025128096
1985	47.649497281408884
1986	49.15861463580802
1987	49.5259886812454
1988	52.13791637044047
1989	52.45933538452952
1990	61.12852664576802
1991	71.6
1992	73.84898710865562
1993	69.18032786885246
1994	63.21167883211679
1995	68.68852459016394
1996	65.54621848739495
1997	66.0968660968661
1998	68.02413273001508
1999	71.45038167938931
2000	66.95652173913044
2001	66.71159029649596
2002	72.6984126984127
2003	69.5024077046549
2004	66.80613668061368
2005	64.95601173020528
2006	68.43702579666162
2007	73.71900826446281
2008	86.41304347826086