merrymaking vs red letter day

merrymaking

noun
  • Joyful festivities, especially as a celebration. 

red letter day

noun
  • A particularly significant day; a day of personal or sectarian celebration. 

  • A day marked in red on calendars; a church feast day. 

How often have the words merrymaking and red letter day occurred in a corpus of books? (source: Google Ngram Viewer )