flatten out vs take off

flatten out

verb
  • To become more even. 

  • To win a fight, usually by punching someone until they are knocked over 

  • To make flat (something rough, folded or bumpy). 

take off

verb
  • To become successful, to flourish. 

  • To depart. 

  • To absent oneself from (work or other responsibility), especially with permission. 

  • To quantify. 

  • To remove. 

  • To leave the ground and begin flight; to ascend into the air. 

  • To imitate, often in a satirical manner. 

How often have the words flatten out and take off occurred in a corpus of books? (source: Google Ngram Viewer )