(s)he vs thon

(s)he

pron
  • He or she; singular of they, used as a gender-neutral form of the third person singular. 

thon

pron
  • they (singular). Gender-neutral third-person singular subject pronoun, coordinate with gendered pronouns he and she. 

  • them (singular). Gender-neutral third-person singular object pronoun, coordinate with gendered pronouns him and her. 

adj
  • Yon. 

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