halcyon days vs seventh heaven

halcyon days

noun
  • A period of calm, usually in the past and often nostalgic. 

  • Period of calm during the winter, when storms do not occur. 

seventh heaven

noun
  • A state of great joy and satisfaction. 

  • The outermost of the heavenly spheres; a dwelling of the angels. 

How often have the words halcyon days and seventh heaven occurred in a corpus of books? (source: Google Ngram Viewer )