decouple vs disjoin

decouple

verb
  • To unlink; to take or come apart. 

  • To muffle the seismic waves of (a nuclear explosion) by performing it underground. 

disjoin

verb
  • To separate; to disunite. 

  • To become separated. 

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