substation vs television station

substation

noun
  • A satellite police station serving one neighborhood or part of a larger jurisdiction. 

  • A site where electricity supplied by long-distance (high-voltage) transmission lines is transformed and/or regulated for local (low-voltage) distribution. 

television station

noun
  • A studio or building from where a television channel is broadcast. 

  • An organization which operates a television channel. 

  • A radio frequency or band assigned to a television broadcaster. 

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