Year	% of total
1970	65.73054466120317
1971	52.1543760605503
1972	54.79479931356093
1973	57.26878999236138
1974	54.712045625901375
1975	56.37598032064515
1976	54.44165942664739
1977	58.79469309007293
1978	59.69475262955507
1979	64.69684671099348
1980	59.92531883754015
1981	56.35049388911515
1982	58.77287065470175
1983	58.305619552278095
1984	53.55305477628839
1985	54.52864369900852
1986	52.61799761521383
1987	57.68391430577321
1988	47.16532887750777
1989	48.37734147488344
1990	12.962962962962962
1991	14.304123711340205
1992	16.157205240174672
1993	18.666666666666668
1994	20.47713717693837
1995	19.886363636363637
1996	20.185185185185187
1997	19.230769230769234
1998	20.422535211267608
1999	19.652173913043477
2000	20.236087689713322
2001	19.063004846526656
2002	18.711656441717793
2003	18.8953488372093
2004	17.696629213483146
2005	17.780748663101605
2006	18.55388813096862
2007	20.32967032967033
2008	22.664835164835164