OC vs of color

OC

adj

  • Of color. 

name

  • Orange County. 

  • OxyContin. 

noun

  • Officer Commanding. 

  • Officer of the Order of Canada. 

of color

adj

  • Nonwhite; of a race other than white, for example black. 

  • Belonging to a category of people with mixed black and white ancestry in the Americas in the 18th and early 19th centuries. 

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