slip through the cracks vs vanish

slip through the cracks

verb
  • To escape notice or lack sufficient attention. 

vanish

verb
  • To become invisible or to move out of view unnoticed. 

  • To become equal to zero. 

  • to disappear; to kidnap 

noun
  • The brief terminal part of a vowel or vocal element, differing more or less in quality from the main part. 

  • A magic trick in which something seems to disappear. 

How often have the words slip through the cracks and vanish occurred in a corpus of books? (source: Google Ngram Viewer )