Retirement tax questions

Hi, I am in the process of filing a Form 8606 for 2021 but I am not sure I understand what basis I should use for Line 2? To recap, I've made a nondeductible contribution for tax years 2021 and 2023. 

"Basis. Your basis in traditional, SEP, and SIMPLE IRAs is the total of all your nondeductible contributions and nontaxable amounts included in rollovers made to these IRAs minus the total of all your nontaxable distributions, adjusted if necessary (see the instructions for line 2, later)."

For Form 8606 2021, is the basis just the contribution I made in that year, or would it include the total of all nondeductible contributions (2021 + 2023)? I did not take any distributions out of any account at any time.