Experience is multiplied by the bracket your level falls in, so the early game is fast and the late game is worth something. The multiplier changes the moment you cross into the next bracket. On top of this, characters up to level 50 get an extra low level bonus.
Level 1 — 45
x600
Level 46 — 79
x400
Level 80 — 129
x300
Level 130 — 160
x200
Level 161 — 190
x160
Level 191 — 220
x80
Level 221 — 250
x40
Level 251 — 280
x30
Level 281 — 300
x20
Level 301 — 350
x16
Level 351 — 400
x10
Level 401 — 450
x6
Level 451 — 500
x4
Level 501+
x2
The rest of the rates are on Server Info.