Mam vs Nana

Mam

name
  • One’s mother. 

  • A Mayan language spoken in the Mexican state of Chiapas and the Guatemalan departments of Quetzaltenango, Huehuetenango, San Marcos, and Retalhuleu. 

Nana

name
  • One's grandmother. 

  • A governess. 

  • A Japanese female given name from Japanese 

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