limerick vs tag line

limerick

noun
  • A humorous, often bawdy verse of five anapaestic lines, with the rhyme scheme aabba, and typically having an 8–8–5–5–8 cadence. 

tag line

noun
  • Synonym of dialogue tag 

How often have the words limerick and tag line occurred in a corpus of books? (source: Google Ngram Viewer )