Attached excel file? This sounds like homework or someone at the office asking for a very odd request.

These questions are overloaded, but they're also horribly out of context. How do you want to rank the impact? Largest change from the average? Largest or smallest value? There's a lot to decide there. Also, dynamic filtering is usually not simple to do via T-SQL without expectations of how you want to filter. That example isn't specific enough to setup a parameterized request against.

This is not consumable, but semi-useful as an example if you wanted short answers to your questions. The problem is, I'm not sure what the question really is. You've asked us how to use a loop. I can explain that, but I don't know what you want to DO with the loop. Not a single question above requires one... and honestly I don't want to do your homework for you if that's what that is, or puzzle out the business requirement if it's not. Define your problem in consumable format (schema/sample data), show us what you've attempted and *specifically* what you're trying to get it to do (not vague examples) and we'll help you out.