subservience vs suzerainty

subservience

noun
  • The state of being subservient. 

suzerainty

noun
  • The status or power of a suzerain. 

  • A relation between states in which a subservient nation has its own government, but is unable to take international action independent of the superior state; a similar relationship between other entities. 

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