How to calculate after-tax portion in my IRA?

Hi there,

 

I have a question on how to calculate my after tax portion as my IRA balance changes.

I had a balance of 100k in my IRA (5k after-tax and 95k pre-tax) at the end of 2023. Now the balance is 110k. Should my after-tax portion remains as 5k? Or it should be 5k* (110k/100k) = 5.5k?

Thanks