dropping vs slumping

dropping

noun
  • The act of something that drops or falls. 

  • Something dropped; a droplet. 

  • A piece of animal excrement; dung. 

slumping

noun
  • the result of a slumping movement, like that of a mountain 

adj
  • something that makes a slumping voice 

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