Aunt Flo vs Mother Nature

Aunt Flo

name
  • A personification of the menstrual period or menstruation. 

Mother Nature

name
  • A personification of nature as woman, stressing fertility and fecundity. Based upon either goddesses of the earth and nature, Gaia, Rhea, or Demeter. 

How often have the words Aunt Flo and Mother Nature occurred in a corpus of books? (source: Google Ngram Viewer )