<prompt> Translate the following text to EnglishLicha ya utafiti mwingi, wataalamu wa uchumi hawajapata sababu moja inayoeleza kwa usahihi kupungua kwa kiwango cha akiba ya kibinafsi.  <response>: Despite a great deal of study, economists have found no single reason that convincingly explains the decline in the personal saving rate. 