Year	% of total
1970	6.473969217493712
1971	6.158701357350615
1972	6.2893373648835835
1973	6.519624406479031
1974	6.869622063560556
1975	7.063943797454672
1976	6.629289414973851
1977	6.45641816114517
1978	6.225403462029761
1979	7.15977460772232
1980	7.167408890109067
1981	6.782884046588573
1982	8.067953390612162
1983	7.8437875399319426
1984	8.824346944290367
1985	7.835307497872954
1986	6.817444952525953
1987	6.165547848174314
1988	5.69643749086781
1989	5.97020477410782
1990	10.077519379844961
1991	11.194029850746269
1992	12.408759124087592
1993	13.970588235294118
1994	15.671641791044777
1995	16.8
1996	13.986013986013987
1997	13.194444444444445
1998	13.953488372093023
1999	12.686567164179104
2000	13.600000000000001
2001	12.121212121212121
2002	11.811023622047244
2003	11.11111111111111
2004	9.701492537313433
2005	8.21917808219178
2006	8.51063829787234
2007	7.894736842105263
2008	7.5