Helen vs Olena

Helen

name

  • A female given name from Ancient Greek. 

  • the daughter of Zeus and Leda, considered to be the most beautiful woman in the world; her abduction by Paris brought about the Trojan War. 

noun

  • Any of various papilionid butterflies of the genus Papilio. 

Olena

name

  • A female given name from Ukrainian, equivalent to English Helen. 

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