Lomapaseo
I guess the answer to your question about the unit of vertical axis is in the Figure 4 of the link given by Safetypee.
About the second part of your question, I guess there is a bit misunderstanding. The following examples may explain better:
At given airplane and given spesific conditions,
1. if pilot wants to stop airplane at 2000m with manual brake and Max Reverse, the Kinetic Energy which airplane has at touchdown is killed by
10% Tire Brake and Rolling drag combination
40% Max Reverse
50% Aerodynamic Drag (= parasit Drag)
Total 100%
2. If the pilot uses only Max Reverse but never wheel brake, the airplane stops near 3000m, and this time the Kinetic Energy which airplane has at touchdown is killed by
3% Only by Rolling drag
42% Max Reverse
55% Aerodynamic Drag (= parasit Drag)
Total 100%
A few word about dragging force of the reverse thrust vs. speed:
I believe Figure 3 at the link is not precisely drawn for engineering purposes but only to give an idea to pilots about the effect of tools they are using for deceleration. But still, the curve for Max Reverse (darker dashed line) shows practically the the dragging force produced by Max Reverse changes only a little bit vs. speed till the moment it is deliberately closed to idle below 80Kts
