Did some math now:
(Edited after receiving the complete numbers until 65)
I'll call the difference from level to level "steps" and the increase in value of the steps "gradient".
The level ride starts harmless, with 120 XPs per level. First
stage for beginners is up to lvl 25 (5290 XPs), with a small gradient
in the steps (505 to lvl 25). From 27 till 75, steps grow by 100 per
level, starting from 1000 to 5700 (the gradient is constantly 100 per
step: 1100, 1200, 1300...). Here, all levels start with 15 as the last
digits, 140215 for lvl 75.
At L38 the step is 2000 per level, slowly rising to 10000 at L80 (210.000 XPs in total).
From there, things really speed up. 20000 XP for 83=>84, 50000 for 89=>90 (total 487.000).
Furtheron, the gradients of the steps stay below 5000 until level
90.
Now the rocket starts: The steps for the following Ls are (in thousands) 58', 78', 99' 121', 144', totalling 1.097.393 XPs at L95.
In this region the steps increase quickly, until 220.000 towards lvl
97.
The rough ladder is (?? indicate guesses)
L30 10.000 XPs
</edit>
L37 20.000 XPs
L49 50.000
L62 100.000
L79 200.000
L85 300.000
L90 500.000
L95 1.000.000
L97 1.500.000
A conservative guess at the next steps is
?L104? 5.000.000
?L108? 10.000.000