Year	% of total
1970	33.41047502122363
1971	38.79594235554081
1972	15.21307924198878
1973	28.467389584751572
1974	37.02909667422343
1975	36.76073531109702
1976	25.38992331914589
1977	15.055838342240918
1978	28.70964890422497
1979	20.225643116491916
1980	20.595314102906805
1981	33.19912885947798
1982	8.222122994428608
1983	20.002011870173455
1984	35.810597325900396
1985	35.067040348107916
1986	21.48135511367343
1987	12.164607231301236
1988	35.0814466686085
1989	32.66297280425122
1990	11.926605504587156
1991	30.985915492957744
1992	42.61363636363637
1993	50.237717908082416
1994	55.934515688949524
1995	60.16746411483253
1996	58.49753694581281
1997	55.93008739076155
1998	54.19354838709678
1999	51.98412698412699
2000	49.795918367346935
2001	46.81440443213297
2002	43.61851332398317
2003	40.660919540229884
2004	37.372262773722625
2005	35.068912710566615
2006	33.33333333333333
2007	32.31240428790199
2008	31.039755351681958