amateurish vs semiprofessional

amateurish

adj
  • Suggesting or reflecting the efforts of an amateur; not seeming professional or polished. 

semiprofessional

adj
  • Of close to professional standard; prosumer. 

  • Of or pertaining to a semiprofession. 

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

noun
  • A semiprofessional person. 

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