Revenue from Different Outlets

There is no across the board percentage. Each person who self-publishes has different percentages. It depends on genre, marketing/promo, "Also Bought" lists, if it's a full moon, etc.

ETA: 2012 and 2013 were very different years for me as shown below.

Amazon
2012 - 86%
2013 - 52%

Apple
2012 - 2%
2013 - 16%

Barnes & Noble
2012 - 7%
2013 - 24%

Kobo/Sony/Smashwords/All Romance/NookPress
2012 - 3%
2013 - 7%

CreateSpace
2012 - 2%
2013 - 1%

I honestly don't think you can generalise. For a long time I made about 90% of my money from B&N (via Smashwords). Now it's about even between B&N and Amazon, with small amounts from Apple and other sellers. But a lot of people will tell you that Amazon dominates their sales.

So much depends on genre, promotions, and previous sales that it's impossible to forecast these things with any accuracy. Add to that the difficulty involved in getting accurate statistics from Amazon et al, and you're going to struggle to find out what's best for you.

If I were self publishing I'd put in the effort and money required to get my books as good as they could be; and then I'd publish in all possible formats, and be pleased with every single sale.