Currency drop rates and level?

When you reach higher levels there are much more items that have a possibility of dropping. For instance, when you are level 45 you can have a drop from any level below that plus a few above. This means that when you are a low level there is many less items possible for a drop increasing the chances for an orb.

I noticed the same thing fairly early on.

Also:

http://www.pathofexile.com/forum/view-thread/272801

Been meaning to test this out with my low level uniques, maby it's a more effienct farming route.