jam tomorrow vs pie in the sky

jam tomorrow

noun
  • Promised benefits that never arrive. 

  • Availability of a resource at a future date. 

pie in the sky

noun
  • A fanciful notion; an unrealistic or ludicrous concept; the illusory promise of a desired outcome that is unlikely to happen. 

How often have the words jam tomorrow and pie in the sky occurred in a corpus of books? (source: Google Ngram Viewer )