tag end vs tail end

tag end

noun

  • The very end. 

  • Something left over. 

tail end

noun

  • The last part of a period of time, event, or situation; the concluding or final part. 

  • The hindmost part of anything (a person, animal, or object), the rear end; the butt, buttocks; hindquarters, rump. 

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