[welder]

Use Time's previous "Most Promising Startups" for their success rate:

2012 - http://www.timeinc.com/pressroom/10nycstartups2012.php

2011 - http://www.timeinc.com/pressroom/events/10nycstartups/

But then, how do you rate a startup as successful? Number of users, revenue, is being acquired a good or bad thing?