<prompt> Translate the following text to SwahiliIf the wage premium is accurately calculated by Professor Wachter, it would be difficult to defend the U.S. postal monopoly on purely economic grounds.  <response>: Kama mshahara wa ziada umehesabiwa kwa usahihi na Profesa Wachter, itakuwa vigumu kutetea udhibiti wa posta ya Marekani kwa misingi ya kiuchumi tu. 