undocumented vs wetback

undocumented

noun
  • Synonym of undocumented immigrant 

adj
  • Lacking instructions or reference material. 

  • Not having official documentation required to legally enter, reside in, or work in a country. 

  • Not having official documents that provide identification, authorization, etc. 

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 undocumented and wetback occurred in a corpus of books? (source: Google Ngram Viewer )