@Stefanos If you want an even parameter curve you can set it up to automatically fill in all the levels.
For example, if you start with 100 max HP and want to gain 5 HP every level, you take 5 x 98 = 490. That gives you the amount of HP that you would gain after leveling up to level 99. Then, add your level 1 value (100 in this case) to get 590 as your value for level 99.
Under the parameter setup, set level 1 to 100, level 99 to 590, and growth type to normal. This will result in every level being an increase of 5 HP.
You can easily change the starting values as well, so if level 1 is 20 for example, level 99 would be 510.
Even if the max level in your game isn't 99, the system still requires the level 99 value to generate the curve.