I'm in the process of writing an evaluation for my assigned areas based on the usage statistics we recently did (see Evaluating Usage). While I was writing this up, I got off on a semi-tanget to find out if there were any standards for percentages of collections that should circulate. If there are, I couldn't find them.
Among the places I looked was ACRL and their standards for Academic Libraries. They basically aim for comparison with peers rather than setting a number or a goal to aim for, so to speak. And, they suggest ratios. Several of them actually. When applied to a small sub-set such as what I'm looking at, well, it's sad and a little depressing.
Then I came across the Library Statistics Program from the National Center for Education Statistics. Interesting website. I did compare my library with several others. Not sure what to do with it, but it is late on a Monday afternoon. It will come to me.
I still don't know if there is a benchmark I should be aiming for or if it really matters. Maybe what matters is knowing how much is circulating, especially since I'm looking at a very specific set of titles. Unofficially, I've selected 30% for my benchmark. If anyone else is doing anything like this, I'd like to hear from you regarding what your library considers good circulation, i.e. 30%, 40%, 50%.