Some of these responses slay me...but I love you all! Actually Yeprem - I think it's a very good, reasonable and fair question to ask. Afterall, you did say "average". But once again, how everyone knew automatically that you were speaking of purchasing or selling and not renting - is beyond me! So, so, so intuit!
But once again- just for grins - say you are asking about renting (because in NY, NY - you pretty much need an agent to assist in even renting an apartment). Most often you will find that fee to be 15% of the annual rent. Although, along with that fee being negotiable as well, there are several scenarios in which that fee is lessened without even any negotiation.
In the case that you are buying or selling a home, the average commission is most often either 6% or 7%. And again, as always - that fee is negotiable (but always up to the closing table- uhmmm, not so much!)
If you would like more explanation or clarity, please don't hesitate to reach out.
All the Best,