numskull vs wild card

numskull

noun
  • A person who refuses to learn or grow mentally. 

  • A dunce, mentally dull or stupid person. 

wild card

noun
  • A competitor or team that is allowed to compete in a tournament despite not reaching the normal standards to qualify for inclusion. 

  • A card that can be assigned any value or used to substitute for any needed card. 

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