avow vs concede

avow

verb
  • To declare openly and boldly, as something believed to be right; to own, acknowledge or confess frankly. 

  • To bind or devote by a vow. 

  • To acknowledge and justify, as an act done. See avowry. 

concede

verb
  • To admit or agree to be true; to acknowledge. 

  • To yield or suffer; to surrender; to grant 

  • To yield or make concession. 

  • (of a bowler) to have runs scored off of one's bowling. 

  • To grant, as a right or privilege; to make concession of. 

  • To have a goal or point scored against 

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