I've seen breakdowns by percentage for certain models. For instance, Plum Crazy was most popular color for 1970 Challengers, with a production around 30%. I don't know where the figures came from. Maybe someone who knows will see this thread, and have your answer.
BTW, GTS has very good information. My experience was that service is unreasonably slow. That was ten years ago, so YMMV. My advice would be avoid paying in advance. Only by requesting order cancellation and a refund many months after placing my order did I receive my book, long after it was useful to me.
