anachronize vs backdate

anachronize

verb
  • To refer to, or put into, a wrong time. 

backdate

verb
  • To give or assign a date to a document that is earlier than the current or true date. 

noun
  • An assigned date that is earlier than the current or true date. 

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