dwindle vs split off

dwindle

verb
  • To break up or disperse. 

  • To decrease, shrink, diminish, reduce in size or intensity. 

  • To lessen; to bring low. 

  • To fall away in quality; degenerate, sink. 

split off

verb
  • To break away from a group or mass. 

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