free rider vs gold digger

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. 

gold digger

noun
  • A person (usually female) who cultivates a personal relationship in order to attain wealth. 

  • Someone who digs or mines for gold. 

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