decouple vs unhook

decouple

verb
  • To unlink; to take or come apart. 

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

unhook

verb
  • To remove from a hook. 

  • To unfasten by means of hooks. 

  • To unfasten the bra of (its wearer). 

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