disperse vs prorate

disperse

verb
  • To scatter in different directions. 

  • To break up and disappear; to dissipate. 

  • To disseminate. 

  • To separate rays of light, etc., according to wavelength; to refract. 

  • To distribute throughout. 

adj
  • Scattered or spread out. 

prorate

verb
  • To divide proportionately, especially by day; to divide pro rata. 

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