Mike,
I do remember seeing exactly what you are looking for many, many
years ago. I'm sure that it must have been in Model Aviation.
And, if I remember correctly, control line membership was
in the single digit %. Rather doubt if it has changed much
since then.
When I was a kid, control line activity was rather modest. I
remember thinking that, when I grew up, it would increase
immensely, and there would be control line flying all over the
place. And then, as the years went by, radio control became
popular, and the ranks of the controliners diminished. Oh
well, it was just the dream of a young kid. What did I know?
Cheers.
Warren Wagner