What determines how much ghost acres one gets from a grab?

I noticed some countries are grabbed for a significant amount of ghost acres and some almost 0 and even 0 at times.

land built is 1 definition, if attacker has alot unbuilt land then ghost acres won't be high and vice versa if defender has then attacker won't gain ghosts that much, if attacks on some very tiny country won't get ghosts at all.

and Dicts get more ghost acres.

And there is ghost acre DR which was posted in the announcements.

http://forums.earthempires.com/...;z=changes-to-ghost-acres

http://forums.earthempires.com/...;z=repost-of-new-lg-rules