This source seems to provide a reasonable explanation.
Sexual violence in South Africa
http://en.wikipedia.org/wiki/Sexual_violence_in_South_Africa#Regional_differences
More than 25% of a sample of 1,738 South African men from the KwaZulu-Natal and Eastern Cape Provinces admitted to raping someone when anonymously questioned; of these, nearly half said they had raped more than one person, according to a non-peer reviewed policy brief issued by the Medical Research Council (MRC).[5] Several news publications wrongly extrapolated these results to the rest of the South African population, given reported rape prevalence several times higher in the two provinces in question than i.e. in Mpumalanga or Northern Province.[6][7]
Sexual violence in South Africa
http://en.wikipedia.org/wiki/Sexual_violence_in_South_Africa#Regional_differences
More than 25% of a sample of 1,738 South African men from the KwaZulu-Natal and Eastern Cape Provinces admitted to raping someone when anonymously questioned; of these, nearly half said they had raped more than one person, according to a non-peer reviewed policy brief issued by the Medical Research Council (MRC).[5] Several news publications wrongly extrapolated these results to the rest of the South African population, given reported rape prevalence several times higher in the two provinces in question than i.e. in Mpumalanga or Northern Province.[6][7]
