validity vs validness

validity

noun
  • The state of being valid, authentic or genuine. 

  • The genuinity - as distinguished from the efficacity or the regularity - of a sacrament as a result of some formal dispositions being fulfilled. 

  • State of having legal force. 

  • A quality of a measurement indicating the degree to which the measure reflects the underlying construct, that is, whether it measures what it purports to measure (see reliability). 

validness

noun
  • the state of being valid 

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