Year	% of total
1970	12.023810573657752
1971	12.019820093820496
1972	12.180452793727607
1973	11.450321883574743
1974	13.045951750545578
1975	12.281268408954595
1976	12.098581129056278
1977	11.290118381680287
1978	12.383954843494191
1979	11.703113424601007
1980	10.380842347539815
1981	11.355484843651361
1982	10.365243662363417
1983	11.122663502315968
1984	11.087646875773405
1985	11.883688257527707
1986	12.365157053999582
1987	12.200612894027687
1988	12.871421924126672
1989	12.156323402937975
1990	11.650153741031772
1991	11.52317880794702
1992	10.799267846247712
1993	10.273972602739725
1994	9.926967811739248
1995	9.854689564068691
1996	8.860435339308578
1997	7.923497267759563
1998	6.916153481762198
1999	6.107398017976492
2000	5.249286184933012
2001	6.455318171376062
2002	7.060361734582697
2003	7.718191377497371
2004	8.394758394758394
2005	8.92083497439937
2006	9.855479727017261
2007	10.180560891279294
2008	10.864999045254917