inject vs knock off

inject

verb
  • To introduce (something) suddenly or violently. 

  • To introduce (code) into an existing program or its memory space, often without tight integration and sometimes through a security vulnerability. 

  • To take or be administered something by means of injection, especially medicine or drugs. 

  • To administer an injection to (someone or something), especially of medicine or drugs. 

  • To push or pump (something, especially fluids) into a cavity or passage. 

  • To introduce or add (something that is different or foreign). 

knock off

verb
  • To accomplish hastily. 

  • To rob. 

  • To defeat. 

  • To halt one's work or other activity. 

  • To have sex with. 

  • To remove, as a discount or estimate. 

  • To make a copy of, as of a design. 

  • To assign (an item) to a bidder at an auction, indicated by knocking on the counter. 

  • To remove by hitting (something, someone) 

  • To kill. 

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