prairie nigger vs timber nigger

prairie nigger

noun
  • A Native American person, especially one from the nations native to Great Plains, such as the Apache, Sioux, Pawnee and Crow. 

timber nigger

noun
  • A Native American person, especially one of Ojibwe descent. 

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