capital punishment vs impalement

capital punishment

noun
  • The practice of putting a person to death as a punishment for a crime. 

impalement

noun
  • The act of torturing or executing someone by impaling them on a sharp stake. 

  • (obsolete) In the sense of an enclosure, the calyx of a flower. In still older works, also spelt empalement (q.v.) 

  • A space fenced in, such as by palings, possibly in the form of an enclosure or cup. 

  • The joining of two coats of arms on one shield. 

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