flak vs vilification

flak

noun
  • Adverse criticism. 

  • A public-relations spokesperson. 

  • Anti-aircraft shell fire. 

  • Ground-based anti-aircraft guns firing explosive shells. 

vilification

noun
  • slanderous or malicious defamation; character assassination 

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