Blackops 2 zombies level up system...:
number of downs x 100 = number of kills you need to level up
example : if you have the skull level, you have 234 downs, and 12'980 kills.. ; you multiply 234 down by 100 = 23'400 kills needed for next level (skull with bowie knife)
i tested it and it works

; the tally marks appear 1 at a time daily.. if you have 5 that means your a daily zombie player
Found by : Rockandkill9