menses vs rag week

menses

noun
  • The discharge of blood mixed with pieces of cellular tissue from the uterus out through the vagina, which occurs roughly every month in uninseminated women; menstrual flow. 

rag week

noun
  • The days of the month when a woman has her period. 

  • An annual event in many universities where students engage in unusual activities to raise money for charity. 

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