quiescent vs tranquil

quiescent

adj
  • Not sounded; silent. 

  • Non-proliferating. 

  • Inactive, quiet, at rest. 

tranquil

adj
  • Calm; without motion or sound. 

  • Free from emotional or mental disturbance. 

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