opinion poll vs questioning

opinion poll

noun
  • A poll organized in an attempt to quantify public opinion on a subject. 

questioning

noun
  • The action of asking questions; a survey; an inquiry. 

  • Interrogation. 

  • The act of challenging, wondering, and doubting. 

adj
  • Unsure of one's sexual orientation and/or gender identity. 

  • Characterized by questions, inquisitiveness, doubt, or wonder. 

How often have the words opinion poll and questioning occurred in a corpus of books? (source: Google Ngram Viewer )