DM vs decimetre

DM

noun
  • A Dr. Martens boot or shoe. 

  • driving motor car 

  • Coordinate terms: PM, IM 

  • adamsite, diphenylaminechlorarsine 

verb
  • To Dungeon Master; to perform as a dungeon master; to run a tabletop role-playing game. 

  • To communicate by direct message, usually on a social website. 

decimetre

noun
  • An SI unit of length equal to 10⁻¹ metres. Symbol: dm 

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