acumen vs mental capacity

acumen

noun
  • Quickness of perception or discernment; penetration of mind; the faculty of nice discrimination. 

  • A bony, often sharp, protuberance, especially that of the ischium. 

  • A sharp, tapering point extending from a plant. 

mental capacity

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