clamp down vs suffocate

clamp down

suffocate

verb
  • To overwhelm, or be overwhelmed (by a person or issue), as though with oxygen deprivation. 

  • To die due to, or kill someone by means of, insufficient oxygen supply to the body. 

  • To destroy; to extinguish. 

  • To suffer, or cause someone to suffer, from severely reduced oxygen intake to the body. 

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