<prompt> Translate the following text to EnglishKwa kuwa kiwango cha akiba ya kibinafsi ni karibu sifuri au hasi, wataalamu wa uchumi wametilia shaka umuhimu wa kipimo cha akiba ya kibinafsi cha NIPA.  <response>: With the personal saving rate around zero or negative, economists have questioned the relevance of the NIPA personal saving measure. 