leniency vs restraint

leniency

noun
  • An act of being lenient. 

  • The quality of mercy or forgiveness, especially in the assignment of punishment as in a court case. 

restraint

noun
  • control or caution; reserve 

  • something that restrains, ties, fastens or secures 

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