titubate vs topple

titubate

verb
  • To stutter, stammer. 

topple

verb
  • To totter and fall, or to lean as if about to do so. 

  • To overturn 

  • To overthrow something. 

  • To push or throw over 

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