refusal vs restriction

refusal

noun
  • The act of refusing. 

  • Depth or point at which well or borehole drilling cannot continue. 

restriction

noun
  • The act of restricting, or the state of being restricted. 

  • A regulation or limitation that restricts. 

  • The mechanism by which a cell degrades foreign DNA material. 

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