Question for CFIs

I was going to ask this question on R.A.Students but I think this is a
more appropriate forum.
After how many hours of dual do you expect the average person to be
ready to solo?
I understand that it is subjective. Not every person is ready to solo
at the same time. There are a number of fundamentals that you require before
you are ready to turn a person loose. There is no urgency in getting
allowing them to solo. Safety is the most important criterium. Etcetras.
Long, long ago an instructor told me a ball-park number of ten hours. He
said he expected to take that long, plus or minus a couple hours, to drill
the fundamentals into a student.
What's been your average?