happening vs on trend

happening

adj
  • Busy, lively; vibrant, dynamic; fashionable. 

  • Trendy, up-to-the-minute. 

noun
  • Something that happens. 

  • A spontaneous or improvised event, especially one that involves audience participation. 

on trend

adj
  • Having characteristics which conform to current fashion trends. 

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