effort vs insouciance

effort

noun
  • An endeavor. 

  • The work involved in performing an activity; exertion. 

  • A force acting on a body in the direction of its motion. 

verb
  • To make an effort. 

insouciance

noun
  • Nonchalance. 

  • Carelessness, heedlessness, indifference, or casual unconcern. 

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