bonanza vs perquisite

bonanza

noun
  • Anything which is a great source of wealth or yields a large income or return. 

  • The point at which two mother lodes intersect. 

  • A rich mine or vein of silver or gold. 

perquisite

noun
  • Any monetary or other incidental benefit beyond salary. 

  • A privilege or possession held or claimed exclusively by a certain person, group or class. 

  • A gratuity. 

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