How much royalties do self published authors earn?

How much royalty do you earn as a  self-published author?  Here is a comparison I made based on what I have been reading and what my income has been:
I'm basing the self-publishing numbers on my own earnings

With a traditional publishing you receive an advance against future earnings. So you have to earn at least that advance in order to receive your first royalty check.

With self publishing there is no advance but you receive royalty checks monthly. 

Now of course none of this hight level arithmetic has merit if it is true that I would sell many, many more books by taking the agent/publishing contract route. 

But would I have. Would they have helped me, or ignored me as they do so many authors? 

There are a lot of ifs and whats, and you certainly don't know the road you have not taken.  All I know is that if they had not and I received such puny royalties on my work, I would be pissed. 

(Traditional publishing royalty deals in percentages depend on author, books and publishers. Yours might be different. This is an average gathered in the industry’s press and blogs.)

source:

Rebecca Brandewyne's website  and my favorite disgruntled papa bear of self publishing, Joe Konrath. who sums in up it this angry/hilarious post, Do Legacy Publishers Treat Authors Badly.