clear up vs straighten out

clear up

verb
  • To clean up. 

  • To depart or disappear. 

  • To clarify, to correct a misconception. 

  • To become free of certain blemishes. 

  • Of stormy weather, to dissipate, to become calm. 

  • To pot all of the remaining balls in a single turn. 

straighten out

verb
  • To tidy, neaten, or organize. 

  • To make straight. 

  • To correct or rectify. 

  • To eliminate confusion from or concerning. 

  • To correct; to stop doing something wrong. 

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