milk saucepan vs water boiler

milk saucepan

noun
  • A small saucepan, often coated with Teflon etc, having a wide lip; typically used to heat milk for drinks 

water boiler

noun
  • An electric device which heats water up to boiling temperature. 

How often have the words milk saucepan and water boiler occurred in a corpus of books? (source: Google Ngram Viewer )