Level 75

Total Experience Required 2,634,723 [confirmed]

Level 100 progress: 38.6%

This is roughly:
Killing 8,783 people in Warzone, or...
Killing 8,962 people in Execution, or...
Killing 7,443 people in Wingman, or...
Scoring 1,881,946 points in Guardian, or...
Scoring 5,727,659 points in Annex, or...
Scoring 3,466,741 points in Submission.

Horde (TU4)

Completing 13,174 waves on Casual, or...
Completing 8,783 waves on Normal, or...
Completing 6,587 waves on Hardcore, or...
Completing 5,270 waves on Insane.

Or a combination of the above. Have fun!