Level 72

Total Experience Required 2,277,409

Level 100 progress: 33.36%

This is roughly the same as:

Killing 3,796 people in Warzone, or...
Killing 3,874 people in Execution, or...
Killing 3,217 people in Wingman, or...
Scoring 813,361 points in Guardian, or...
Scoring 2,475,445 points in Annex, or...
Scoring 1,498,296 points in Submission.

Horde (TU4)

Completing 5,694 waves on Casual, or...
Completing 3,796 waves on Normal, or...
Completing 2,847 waves on Hardcore, or...
Completing 2,278 waves on Insane.

Or a combination of the above. Have fun!