free lunch vs technique

free lunch

noun
  • Something obtained without any payment, obligation or effort. 

technique

noun
  • A method of achieving something or carrying something out, especially one requiring some skill or knowledge. 

  • Practical ability in some given field or practice, often as opposed to creativity or imaginative skill. 

  • The practical aspects of a given art, occupation etc.; formal requirements. 

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