Year	% of total
1970	9.60173911331176
1971	9.185852054268244
1972	9.145068251605174
1973	9.227795665350955
1974	9.226161578839248
1975	8.687371501048098
1976	8.78597452764595
1977	8.73456059385158
1978	8.669135406324568
1979	8.723791922237016
1980	8.897491855798199
1981	8.934410854175706
1982	9.046780309579395
1983	8.999185281327096
1984	8.973883663960851
1985	8.96095286214622
1986	9.01438377459602
1987	8.833661140777343
1988	15.835702514421266
1989	21.3576938082479
1990	7.5736325385694245
1991	7.790368271954675
1992	5.442176870748299
1993	6.528662420382165
1994	7.168458781362006
1995	7.751937984496124
1996	7.8
1997	7.8156312625250495
1998	8.041237113402062
1999	8.296943231441048
2000	8.88382687927107
2001	9.420289855072465
2002	9.59232613908873
2003	9.692671394799055
2004	10.070257611241217
2005	11.347517730496454
2006	11.217183770883054
2007	10.739856801909307
2008	11.166253101736972