How to take a distribution from a ROTH before 59.5

I want to take a distribution from my ROTH IRAs that is less than the conversion amounts I did that were all 5 years and older plus my initial contribution 20 years ago. I am not 59.5. I believe I can do that without tax or penalties but how do I prove that the distribution is less than the conversions and contribution? I think I need to know when each contribution and conversion was made. Do I need to know it? Is there a way to get that info, if you don't have your tax paperwork or forms from way back 20 years ago?