introduce vs thresh out

introduce

verb
  • To bring (something) into practice. 

  • To cause (someone) to be acquainted (with someone else). 

  • To add (something) to a system, a mixture, or a container. 

  • To make (something or someone) known by formal announcement or recommendation. 

thresh out

verb
  • To extract or remove by threshing. 

  • To thrash out. 

How often have the words introduce and thresh out occurred in a corpus of books? (source: Google Ngram Viewer )