Sambo vs tar baby

Sambo

noun
  • A black person, especially one who is accommodating or servile towards whites; an Uncle Tom. 

name
  • A nickname from the given name Samantha. 

  • A Russian martial art and combat sport. 

  • A nickname from the given name Samuel. 

tar baby

noun
  • A black person. 

  • A difficult, abstract problem that worsens as one attempts to handle it; a "sticky" situation, especially one where attempts to make it better only make it worse. 

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