Chink vs ching chong

Chink

noun
  • A person of perceived Chinese ethnicity. 

adj
  • Chinese, or perceived to be Chinese. 

ching chong

noun
  • A Chinese or other Asian person. 

intj
  • Mimicking Chinese, Korean, Thai or other East/Southeast Asian speech. 

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