dead on vs on the level

dead on

adj

  • very accurate 

adv

  • exactly at 

on the level

prep

  • Synonym of on the square (“discreet reference to freemasonry”) 

  • Honest(ly), sincere(ly), straightforward(ly), fair(ly). 

How often have the words dead on and on the level occurred in a corpus of books? (source: Google Ngram Viewer )