acquaintance vs skill in

acquaintance

noun
  • A state of being acquainted with a person; originally indicating friendship, intimacy, but now suggesting a slight knowledge less deep than that of friendship; acquaintanceship. 

  • Personal knowledge (with a specific subject etc.). 

  • Such people collectively; one's circle of acquaintances (with plural concord). 

  • A person or persons with whom one is acquainted. 

skill in

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