hygge vs icing on the cake

hygge

noun

  • Cosiness, comfort, contentment, conviviality. 

adj

  • Cosy, convivial. 

icing on the cake

noun

  • Something that intensifies the appreciation of something already good. 

How often have the words hygge and icing on the cake occurred in a corpus of books? (source: Google Ngram Viewer )