cleartext vs text file

cleartext

noun
  • The unencrypted form of an encrypted text; plain text 

text file

noun
  • A data file containing only plain, human-readable text, distinct from documents with embedded formatting 

  • A data file in a character encoding that allows it to be read in non-specialised text editor. 

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