superlative vs top-class

superlative

adj
  • Exceptionally good; of the highest quality; superb. 

  • Of or relating to a superlative. 

noun
  • The extreme (e.g. highest, lowest, deepest, farthest, etc) extent or degree of something. 

  • An adjective used to praise something exceptional. 

  • The form of an adjective that expresses which of several items has the highest degree of the quality expressed by the adjective; in English, formed by appending "-est" to the end of the adjective (for some short adjectives only) or putting "most" before it. 

top-class

adj
  • Of the highest quality. 

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