lynch vs string up

lynch

verb
  • To execute (somebody) without a proper legal trial or procedure, especially by hanging and backed by a mob. 

string up

verb
  • To kill (a person) by hanging, especially to lynch. 

  • To concatenate; to link in a line. 

  • To suspend by means of rope, cord or similar material. 

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