Delhi belly vs Montezuma's revenge

Delhi belly

noun
  • Digestive illness or diarrhoea, especially if suffered by a visitor to India. 

Montezuma's revenge

noun
  • Diarrhea experienced by tourists after drinking water or eating food in Mexico as a result of a microorganism to which native Mexicans are immune. 

How often have the words Delhi belly and Montezuma's revenge occurred in a corpus of books? (source: Google Ngram Viewer )