SM vs switching

SM

symbol
  • service mark 

switching

noun
  • Back-and-forth movement of an animal's tail, etc. 

  • The transference of an investment from one fund to another. 

  • The movement of a locomotive from one track to another. 

  • Change from one product/service provider to another. 

  • Corporal punishment by use of a switch (twig or twigs). 

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