illegal immigrant vs wetback

illegal immigrant

noun
  • Someone who has immigrated into a country by bypassing customs and immigration controls. 

wetback

noun
  • A Mexican or Central American who illegally enters the United States of America from its southern border. 

  • A person of the mestizo race; a mojado. 

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