conferrer vs sustainer

conferrer

noun
  • A person who confers or bestows something 

sustainer

noun
  • A person or thing that sustains. 

  • A person who makes regular donations, especially to a public radio or television station. 

  • A rocket engine that remains with a spacecraft during its ascent after the separation of the booster engines. 

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