I was getting approx 36k/h at 60 range. It's fairly fast xp, and easily botted.
I've heard the xp/h can go upto 50k/h. I havn't personally seen it go any higher.
Tip: Try to get as much range bonus as possible, use a longbow / dark bow etc.
Just like other people said, range bonus does in fact help, so it is highly recommended to use best range gear possible if you can afford it (dark bow, amulet of ranging, robin hat, etc.). The Exp/hour ranges from 30k-50k at the max.