blotter vs police blotter

blotter

noun
  • A daily register of arrests and other events in a police station. 

  • A register of the related events made in the form of the list of times and brief descriptions. 

  • A piece of blotting paper in a pad as a piece of desk furniture. 

  • A portion of blotter acid. 

police blotter

noun
  • A register, maintained by the desk sergeant, of people arrested or brought in for questioning to a police station; (UK) charge sheet. 

  • A newspaper column publishing highlights therefrom. 

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