Level 73

Total Experience Required 2,393,011

Level 100 progress: 35.06%

This is roughly the same as:

Killing 3,989 people in Warzone, or...
Killing 4,070 people in Execution, or...
Killing 3,380 people in Wingman, or...
Scoring 854,647 points in Guardian, or...
Scoring 2,601,099 points in Annex, or...
Scoring 1,574,350 points in Submission.

Horde (TU4)

Completing 5,983 waves on Casual, or...
Completing 3,989 waves on Normal, or...
Completing 2,992 waves on Hardcore, or...
Completing 2,394 waves on Insane.

Or a combination of the above. Have fun!