hammered dulcimer vs qin

hammered dulcimer

noun
  • A type of dulcimer whose metal strings are stretched over a trapezoidal sounding board that has two bridges, one bass and one treble, set on a stand and played with small mallet-like hammers. 

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 hammered dulcimer and qin occurred in a corpus of books? (source: Google Ngram Viewer )