questioning vs self-questioning

questioning

noun
  • The act of challenging, wondering, and doubting. 

  • Interrogation. 

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

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

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

self-questioning

noun
  • contemplation on one's actions, beliefs, etc. 

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