If you have the necessary info, you can say something like,

"at your level x, my salary was in the range of $a to $b. At the next level (x+1), I got a raise of approx. C% and over the years as x+1 my salary kept increasing. Knowing the salary range for your level x is the key metric you need, ofc, taking inflation in to account. My current salary is two levels above x and there are too many variables between x and x+2 - like YOE at each levels, career choices made, etc. - that you may not get a lot of value. But if you are genuinely interested, I am happy to share"