ability vs effectivity

ability

noun
  • The quality or state of being able; capacity to do or of doing something; having the necessary power. 

  • A unique power of the mind; a faculty. 

  • A skill or competence in doing; mental power; talent; aptitude. 

  • Physical power. 

  • The legal wherewithal to act. 

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 ability and effectivity occurred in a corpus of books? (source: Google Ngram Viewer )