HB vs dimber mort

HB

adj
  • hard black (describing a pencil that makes lighter marks than a grade B, but darker marks than a grade H pencil). 

noun
  • A hot babe, someone pickup artists try to seduce. (Usually followed by a number in the 1-10 scale of physical beauty, e.g. HB10.) 

dimber mort

How often have the words HB and dimber mort occurred in a corpus of books? (source: Google Ngram Viewer )