brandmark vs registered trademark

brandmark

noun
  • The logo of a brand 

verb
  • To name or mark by branding; to give a brandmark to. 

registered trademark

noun
  • A trademark that has been officially registered with the government by its owner. Indicated by the symbol ®. 

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