proprietary rights vs tenure

proprietary rights

tenure

verb
  • To grant tenure, the status of having a permanent academic position, to (someone). 

noun
  • A status of possessing a thing or an office; an incumbency. 

  • A period of time during which something is possessed. 

  • A right to hold land under the feudal system. 

  • A status of having a permanent post with enhanced job security within an academic institution. 

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