Level 76

Total Experience Required 2,761,044 [confirmed]

Level 100 progress: 40.45%

This is roughly:
Killing 9,204 people in Warzone, or...
Killing 9,392 people in Execution, or...
Killing 7,800 people in Wingman, or...
Scoring 1,972,175 points in Guardian, or...
Scoring 6,002,270 points in Annex, or...
Scoring 3,632,953 points in Submission.

Horde (TU4)

Completing 13,806 waves on Casual, or...
Completing 9,204 waves on Normal, or...
Completing 6,903 waves on Hardcore, or...
Completing 5,523 waves on Insane.

Or a combination of the above. Have fun!