I'm afraid that my first response is more of a guess, but I don't have that many orchids, so I probably remember how many I lost... but in the range of 5 - 10%. With less orchids its easier to take care of them. Most of the ones I've had trouble with came to me really small or Oncidium/Odontoglossum types. I have a few of those that are pretty iffy yet, but am starting to do better with them as I spray them more for fungal problems and am moving them to S/H, which seems to help them here. As I experiment more, I lose more too.

I keep notes too, just working on updating and sorting my notes. I've moved from a lab book to a 3 ring binder and plan to print out and ad pictures of each one as they bloom too. Maybe I can do numbers with stickers that I can remove or cover up as the collection shifts over time. Any ideas out there?