registered trademark vs sole trader

registered trademark

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

sole trader

noun
  • A type of enterprise or proprietorship which is owned by one person who is fully liable for the company's debts and fulfilment of contracts with his/her personal wealth unless incorporated. 

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