mulish vs submissive

mulish

adj

  • Characteristic of a mule; stubborn, obstinate, or intractable 

submissive

adj

  • Meekly obedient or passive. 

noun

  • One who submits. 

  • One who submits to a dominant partner in BDSM practices. 

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