Elena vs Yelena

Elena

name
  • A female given name from Italian, Spanish, or Ancient Greek. 

  • A surname originating as a matronymic. 

Yelena

name
  • A transliteration of the Russian female given name Еле́на (Jeléna), equivalent to Helen. 

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