Year	% of total primary
1971	34.3524589538574
1972	25.4868602752686
1973	25.9861392974854
1974	24.9937496185303
1975	27.8832702636719
1976	22.887149810791
1986	20.9794006347656
1991	22.8018703460693
1993	22.3459796905518