Just to clarify, the Summer Pool and August Reconsideration Pool are slightly different. The Summer Pool is for offer holders who have not met the conditions set for them, whereas the August Reconsideration Pool is for applicants who have been rejected in January but meet certain widening participation criteria and go on to meet or exceed the typical offer for their course. You're not automatically entered in the August Reconsideration Pool - you have to put yourself forward in August if you are eligible and get the grades.
Crucially, the August Reconsideration Pool is what used to be called Adjustment. Any statistics you find for Adjustment at Cambridge are likely to be more applicable to your situation than statistics about the Summer Pool. Hope this helps!