<prompt> Translate the following text to EnglishWakati kiasi cha kila kituo kinapozidi kuongezeka na chanjo inakaribia asilimia 100, kutofautiana kwa kiasi cha gharama ya upatikanaji inakaribia sifuri.  <response>: As volume per stop grows and coverage approaches 100 percent, the volume variability of access cost approaches zero. 