For as long as many of us can remember, it's been red, yellow, green. Granted, in some places, you see a separate part of the light that shows protected greens or yellow or whatever. But generally, the 3-color combo is what we've known.
Now, whether some people in the Dallas and Tyler, Texas area actually understand what those colors MEAN is another conversation entirely. Yeah, we're looking at you, yellow light speeder-uppers! (That's a technical term, of course.)