Why is it that in most of the USA's TV commercials 96 Percent (P/C) of the actors are ALWAYS Caucasian and the other 4 P/C are HALF black.?

Are you racist white people that afraid of representing other races (e.g., fully blacks, Chinese, Mexicans, Native American Indians, Jamaicans, Haitians, Japanese, etc.)? You racist white people are cruel. But don't worry, I'm leaving YOUR (haha!) country for Mexico City next month. And this black male online English teacher, who makes $15 dollars per hour, WILL let the door hit me on the way out? Why, you say? Because I am ready to get the hell up out of AmeriKKKa.