Sellotape vs masking tape

Sellotape

noun
  • A brand of adhesive tape (and similar products) similar to Scotch tape (US). 

masking tape

noun
  • A pressure-sensitive tape made of a thin and easy-to-tear paper characterized by its ease of removal, not leaving adhesive behind. It is used mainly in painting, to mask off areas that should not be painted. 

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