first-rate vs top-grade

first-rate

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

  • 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. 

noun
  • A first-rate ship of the line. 

top-grade

adj
  • Of the highest quality. 

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