SC vs softcover

SC

noun
  • supercentenarian 

  • simple cubic 

  • subcutaneous injection 

  • stem cell 

  • supercapacitor 

  • supercluster (of galaxies), galaxy superclsuter 

  • superconductor 

adj
  • subcutaneous 

softcover

noun
  • A book having such covers. 

adj
  • Having covers made of paper or thin cardboard; paperback. 

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