sheng vs xiao

sheng

noun
  • A Chinese wind instrument, a free-reed mouth organ consisting of 13 or more bamboo pipes of various lengths, which are fixed at their bases in a wind chest made from a dried gourd (or, more recently, wood or chrome-plated brass). 

xiao

noun
  • A type of Chinese flute. 

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