halcyon days vs yesteryear

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. 

yesteryear

noun
  • Past years; time gone by; yore. 

  • Last year. 

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