dulcimer vs qin

dulcimer

noun
  • A stringed instrument, with strings stretched across a sounding board, usually trapezoidal, played by plucking on the strings (traditionally with a quill) or by tapping on them (in the case of the hammer dulcimers). 

qin

noun
  • Any of several traditional Chinese musical instruments, most commonly the seven-stringed instrument more specifically called the guqin. 

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