I have no hard numbers but I will explain the reasoning for the choices.
My recommendation: Flat attack speed runes in every slot.
The reasoning. His passive scales perfectly with AS and most Warwick builds are based around on hit effects. (Wits end, his passive, Bloodrazor). AS helps him clear camps faster, gives him more sustain and scales extremely well late game.
Armour pen runes - These are a no go in my opinion. 10 Armour pen is enough for jungle creeps to have 0 armour, however Warwick doesn't scale very well with these runes. They may be good for optimal jungle clearing time, however I wouldn't recommend them due to their usefulness falling off pretty hard late game.
Attack damage runes - Warwick doesn't scale so well with AD, so as above, I would not recommend them.
Flat armour seals - I would recommend these on every jungler, except for Warwick. He has build in sustain. You will want to build a wiggles anyway, so the cloth armour will be more than enough for you.
Magic pen runes - These are very strong for lanewick and scale well late game. However, they are not optimal for faster jungle clearing times.
Magic resistance glyphs - These are an option instead of attack speed glyphs. This decision makes your clear time slower. Warwick tend to end up with a fair amount of magic resist through most builds anyway, so I'd say AS runes are preferable unless you are against an extremely AP heavy team.
Movement speed Quints - These are another option for WW. He will be able to travel between camps faster as well as help his ganks. His bloodscent makes these a bit redundant later on in the game as you will probably be moving faster than everyone else already anyway. Attack speed quints are probably still preferable due to sustain they give.