bagpipes vs pipes

bagpipes

noun
  • A musical wind instrument of Celtic origin, possessing a flexible bag inflated by bellows, a double-reed melody pipe and up to four drone pipes; any aerophone that produces sound using air from a reservoir to vibrate enclosed reeds. 

pipes

noun
  • A single pipe organ. 

  • Biceps. 

  • One's vocal capacity. 

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