hobbyist vs semiprofessional

hobbyist

noun
  • A person who is interested in an activity or a subject as a hobby. 

  • A client in a girlfriend experience. 

semiprofessional

noun
  • A semiprofessional person. 

adj
  • Of or pertaining to a semiprofession. 

  • Paid as a professional but on a part-time basis. 

  • Of close to professional standard; prosumer. 

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