disjoin vs split up

disjoin

verb
  • To separate; to disunite. 

  • To become separated. 

split up

verb
  • separate, disassociate, cause to come apart. 

  • Cease to be together, break apart from the group. 

adj
  • Divided or separated. 

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