Your state’s rate is statutory, is based on the rate for 5-year Treasury Notes and changes twice a year. It’s very possible that the rate was stated in the judgment Order but, if it wasn’t, it seems safe to infer that it was a recent judgment.
Use the suggested PDF link. Find your interest rate, multiply the judgment amount by that rate, divide by 365 to get the daily rate and multiply by 21 days or however many it takes to prepare the paperwork.