Stop Loss formula

I dont really even know if this is the right place to go to but I have a spreadsheet I was given which shows different trades across 1000 days

The values in the sheet show the trade value entering and exiting the trade but it does not have a stop loss set and I was wondering if you could have a stop loss based on an avg of the losing exit trades which may have been exited anywhere from half a percent to all the way to 11% from the entry 

Is there a formula or something I could use to establish a stop loss percentage value each time I enter a trade rather than just assigning some arbitrary number?

If someone could sit down and look at the sheet, I would be more than happy to pay you for your time and tell me yes it can be done or no it cant.

Name your fair rate.

Thank you