below par vs underaverage

below par

prep
  • Not up to the average or normal standard. 

  • (of a score) Less than par for the hole or course (which in golf, means better than par). 

  • Having a price below its face value. 

underaverage

adj
  • Below average. 

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