helotism vs subjection

helotism

noun
  • A form of mutualism in which one species is forced to perform tasks for another, for their mutual benefit 

  • The permanent oppression of a nominally free group of people 

subjection

noun
  • The act of bringing something under the control of something else. 

  • The state of being subjected. 

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