mulling over vs reasoning

mulling over

reasoning

noun
  • A Rastafari meeting held for the purposes of chanting, prayer and discussion. 

  • The deduction of inferences or interpretations from premises, abstract thought, ratiocination; (countable) any instance of this, especially as a process leading to an action, motive. 

How often have the words mulling over and reasoning occurred in a corpus of books? (source: Google Ngram Viewer )