crack the whip vs restrain

crack the whip

verb
  • To make harsh demands in a position of leadership. 

restrain

verb
  • To restrict or limit. 

  • To control or keep in check. 

  • To deprive of liberty. 

  • To strain again. 

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