go the way of the dodo vs stagnate

go the way of the dodo

verb
  • To go extinct or become obsolete; to fall out of common practice or use; to become a thing of the past. 

stagnate

verb
  • To cease to develop, advance, or change; to become idle. 

  • To cease to flow or run. 

  • To be or become foul from standing. 

How often have the words go the way of the dodo and stagnate occurred in a corpus of books? (source: Google Ngram Viewer )