decouple vs loosen

decouple

verb
  • To unlink; to take or come apart. 

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

loosen

verb
  • To become unfastened or undone. 

  • To make loose. 

  • To free from restraint; to set at liberty. 

  • To relieve (the bowels) from constipation; to promote defecation. 

  • To become loose. 

  • To disengage (a device that restrains). 

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