Just putting down some numbers here, currently I'm getting about 300-400 AXP per kill... say 350 average...
That would mean this ammount of kills....
Level - AXP needed = Total kills
01 - 00001500 = 5 kills!
02 - 00009000 = 26 kills!
03 - 00022500 = 65 kills!
10 - 00285000 = 814 kills!
15 - 00697410 = 1993 kills!
20 - 01963419 = 5610 kills!
25 - 05527621 = 15794 kills!
30 - 15561937 = 44462 kills!
Lets hope the AXP scales upwards as you get higher levels!
I can easily see myself getting to level 15 with this kind of AXP, since im already at level 9 (atm) and ive got 997 kills, and 6 deaths so far...
Note that my first 2 levels came with the uber low AXP rewards, and my deaths, thats why I am a bit behind the scheme above, but getting to some 2k alien kills will not be hard at all imo, ~45000 kills though... OMG!