best man vs usher

best man

noun
  • The primary attendant to the groom in a wedding ceremony. 

  • Used other than figuratively or idiomatically: see best, man. 

usher

noun
  • A male escort at a wedding. 

  • A doorkeeper in a courtroom. 

  • A person, in a church, cinema etc., who escorts people to their seats. 

verb
  • To lead or guide somewhere. 

  • To precede; to act as a forerunner or herald. 

  • To accompany or escort (someone). 

  • To guide people to their seats. 

How often have the words best man and usher occurred in a corpus of books? (source: Google Ngram Viewer )