bloodsucker vs free rider

bloodsucker

noun
  • One who attempts to take as much from others as possible; a leech. 

  • An animal that drinks the blood of others, especially by sucking blood through a puncture wound; a hemovore. 

  • The changeable lizard (Calotes versicolor). 

  • A vampire. 

  • Any parasite. 

free rider

noun
  • Someone who obtains goods or services legally without paying. 

  • A worker at an open shop who is able to enjoy the benefits negotiated by a union without being a member of the union. 

  • One who obtains benefit from a public good without paying for it directly. 

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