Personally, I sign up to a lot of programs, don't get around to putting up links right away, and eventually forget I've signed up at all. I suspect there are others like me.

20+ but that also includes some dutch sponsors

I've signed up to a zillion sponsors but only promoting 15 or so :)

i actively promote probably around 200 different sponsors, prolly only signed up to about 20 or so this year also

We send traffic to about 25 different sponsors, but make the majority of our money off of about 12 of them.

I think you probably should have said "How many sponsors are you signed up for and actively sending traffic?". That would be more informative, because I for one, signed up to a total of probably 50 sponsors, but only send traffic to a handful.