Read this and answer the question. If the question is unanswerable, say "unanswerable".

Up to 1990, English, German and Afrikaans were official languages. Long before Namibia's independence from South Africa, SWAPO was of the opinion that the country should become officially monolingual, choosing this approach in contrast to that of its neighbour South Africa (which granted all 11 of its major languages official status), which was seen by them as "a deliberate policy of ethnolinguistic fragmentation." Consequently, SWAPO instituted English as the sole official language of Namibia though only about 3% of the population speaks it as a home language. Its implementation is focused on the civil service, education and the broadcasting system. Some other languages have received semi-official recognition by being allowed as medium of instruction in primary schools. It is expected of private schools to follow the same policy as state schools, and "English language" is a compulsory subject. As in other postcolonial African societies, the push for monolingual instruction and policy has resulted in a high rate of school drop-outs and of individuals whose academic competence in any language is low.

There was a high rate of what due to monolingual instruction?
school drop-outs