sie vs ze

sie

pron
  • Gender-neutral subject pronoun, grammatically equivalent to the gendered pronouns he and she 

noun
  • A drop. 

verb
  • To strain, as milk; filter. 

  • To drop, as water; trickle. 

  • To fall, as in a swoon; faint. 

  • To sift. 

  • To sink; fall; drop. 

ze

pron
  • a gender-neutral third-person singular subject pronoun, equivalent to singular they, and coordinate with gendered pronouns he and she. 

noun
  • The name of the Cyrillic script letter З / з. 

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