autobiography vs novella

autobiography

noun
  • Biographies of this kind regarded as a literary genre. 

  • A self-written biography; the story of one's own life. 

novella

noun
  • A short novel or long short story. 

  • Synonym of novel (“new legal constitution in Ancient Rome”) 

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