Year	% of total
1970	9.843415182658003
1971	9.64840470549435
1972	8.5254868645235
1973	9.478933409348574
1974	9.757118291463149
1975	11.519770800693095
1976	11.540758371720148
1977	11.750176804606403
1978	12.182509631017885
1979	12.243451826203373
1980	12.308709936806682
1981	12.191657325152049
1982	12.189665276571098
1983	12.11635854850205
1984	11.781857547204947
1985	11.441448745968078
1986	11.17713071012249
1987	11.152482053179124
1988	11.406640836336553
1989	11.894667565603312
1990	8.937314005951809
1991	9.115853658536585
1992	7.78619053000339
1993	7.849158580027024
1994	7.728337236533958
1995	8.305804624823029
1996	8.616968288228458
1997	8.501879362806514
1998	8.901441371250488
1999	9.53252032520325
2000	9.487027134085958
2001	9.201877934272302
2002	9.30451127819549
2003	9.171762090050027
2004	10.237329042638779
2005	10.471414242728185
2006	10.915281393951533
2007	10.347535833496957
2008	9.53240657158332