<prompt> Translate the following text to EnglishHii ni kwa sababu ya viwango vya juu vya ndani kwa nchi hizi mbili ikilinganishwa na viwango vya ndani vya Marekani na kwa sehemu kwa tofauti katika kiasi cha barua iliyobadilishwa kati ya Marekani na nchi hizi mbili.  <response>: This is due partly to the relatively high domestic rates for these two countries compared to U.S. domestic rates and partly to the disparity in the mail volumes exchanged between the U.S. and these two countries. 