menstrual period vs rag week

menstrual period

noun
  • An event of a woman's discharging of menstrual flow of blood and cells. 

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 menstrual period and rag week occurred in a corpus of books? (source: Google Ngram Viewer )