clear out vs slope off

clear out

verb
  • to leave quickly 

  • to become empty 

  • to remove or eject (from), especially forcibly 

  • To rob or steal from (someone). 

  • to completely empty 

  • To be victorious in gambling against (someone). 

slope off

verb
  • To depart quietly, without being noticed. 

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