unemotional vs unflappable

unemotional

adj
  • Showing little or no feeling. 

  • Reasoned and objective, involving reason or intellect rather than feelings. 

unflappable

adj
  • Remaining composed and level-headed at all times; impossible to fluster; not becoming frustrated or irritated easily. 

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