fleetness vs slowness

fleetness

noun
  • The quality of being fleet or swift; rapidity. 

slowness

noun
  • A unit, the reciprocal of velocity, that delineates the amount of time required for an object to travel a given distance. 

  • The quality or state of being slow. 

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