uncoil vs unravel

uncoil

verb
  • To unwind or untwist oneself. 

  • To unwind or untwist (something). 

unravel

verb
  • To become undone; to collapse. 

  • To separate the threads (of); disentangle. 

  • To become separated; (of something woven, knitted, etc.) to come apart. 

  • To separate the connected or united parts of; to throw into disorder; to confuse. 

  • To clear from complication or difficulty; to unfold; to solve. 

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