This is a great question. Would your focus be for a specific country or region? I'm assuming this question is for online business only?
However, If you're looking into accelerators, that's a whole different thing. My three favorites are Y Combinator, Techstars, and 500 Startups.
Those threes have their system where they invest capital in the selected startup companies, and they go through a mentorship program that ends on a Demo Day. You can find Techstars' stats and numbers on this page: http://www.techstars.com/companies/
If you're looking into the idea of creating an incubator, I would suggest you to do a coworking space or an accelerator (if you have the right team and platform to do so).
Now the question in an year old the entire scenario has changed. If you are looking for an updated answer then you must let me know about what is your criteria of defining success for incubators:
1. No. of Investments
3. No of Exits
I can answer you appropriately after that.