<prompt> Translate the following text to EnglishKwa mfano, utendaji bora wa scrubber na uwezo wa baadhi ya makampuni ya kubadili kwa mafuta ya chini ya sulfuri chini ya Programu ya Mvua ya Asidi ilikuwa sababu ya gharama ya programu hiyo ilikuwa chini ya makadirio.  <response>: For example, improved scrubber performance and the ability of some firms to switch to lower sulfur fuels under the Acid Rain Program were reasons the cost of that program were less than projected. 