Chinese mile vs ri

Chinese mile

noun
  • A li, a traditional Chinese unit of distance equal to 1500 Chinese feet or 150 zhangs, now standardized as a half-kilometer (500 meters). 

ri

noun
  • Synonym of li as a Korean unit of distance equivalent to about 393 m. 

  • The solfeggio syllable used to indicate the sharp of the second note of a major scale, enharmonic to me. 

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