imperturbability vs presence of mind

imperturbability

noun
  • A state of calm, unruffled self-assurance; aplomb, composure. 

presence of mind

noun
  • Focused alertness, quick-thinking resourcefulness, stability of thought and feeling, or good sense, especially in spite of circumstances which are distracting, stressful, or otherwise challenging. 

How often have the words imperturbability and presence of mind occurred in a corpus of books? (source: Google Ngram Viewer )