cap it all off vs strike someone when they are down

cap it all off

verb
  • To surpass or outdo something. 

  • To finish or complete something; to add a finishing touch. 

strike someone when they are down

verb
  • Synonym of kick someone when they are down (“make things worse for someone in a difficult position”) 

How often have the words cap it all off and strike someone when they are down occurred in a corpus of books? (source: Google Ngram Viewer )