Holocaust vs the Nazi genocide

Holocaust

name
  • The systematic mass murder (genocide) of six million Jews perpetrated by Nazi Germany shortly before and during World War II. 

  • The systematic mass murder (democide) of eleven million people, namely six million Jews and five million others (including Romanis, Slavs, homosexuals, and people with physical and mental disabilities), perpetrated by Nazi Germany shortly before and during World War II. 

the Nazi genocide

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