competency vs effectivity

competency

noun
  • The ability to perform some task; competence. 

  • Implicit knowledge of a language’s structure. 

  • Meeting specified qualifications to perform. 

effectivity

noun
  • The ability or power to be effective. 

  • [Technical documentation] An indication of the product, procedure, or timescale for which an item of information is applicable or effective. 

  • A measure of the effectiveness of something. 

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