<prompt> Translate the following text to EnglishKwa sababu ya gharama za posta za Marekani ni wazi zaidi katika ulimwengu wa viwanda, sisi kutumia data ya Marekani kutoka 1999 kama inapatikana katika kesi ya hivi karibuni ya omnibus rate Dok.  <response>: Postal Service has been studied extensively and because U.S. postal costs are the most transparent in the industrialized world, we use U.S data from 1999 as provided in the most recent omnibus rate proceeding, Docket No. 