first-rate vs low-class

first-rate

noun
  • A first-rate ship of the line. 

adj
  • Of a Royal Navy ship of the line in the Napoleonic Era: having at least 100 guns across three gun decks, a complement of 850–875, and weighing approximately 2,500 tons burthen. 

  • Superb, exceptional; of the best sort; very high quality. 

low-class

adj
  • Lacking social rank or respectability. 

How often have the words first-rate and low-class occurred in a corpus of books? (source: Google Ngram Viewer )