deadline vs tail end

deadline

noun
  • A time limit in the form of a date on or before which something must be completed. 

verb
  • To render an item non-mission-capable; to ground an aircraft, etc. 

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 deadline and tail end occurred in a corpus of books? (source: Google Ngram Viewer )