We're only a small school. We usually sell approximately eighty or so on the run-up to Christmas. I have a vague recollection of selling a couple of hundred at a flying club back in the late '90s. As for the number that don't get used. There's a few. I'm always extra busy just before the vouchers expire. It's hard to remain enthusiastic when you know that the person's only booked in after being nagged to do so by whoever bought the voucher in the first place.