Cs cs cs
 

What is the average cs for EACH lane?

EDIT;;
at 20 mins.

160-180 CS in every lane, excluding the jungler.

I would say that is near optimal, not average.

Average probably 120-150 for the AD carry bot, a little more for the solo top, and about 150-180 for the AP mid. But it depends heavily on the champion. If you're someone like AP ezrael mid who has horrible farming potential it's going to be lower, wheras if you are Singed, Morde or Anivia who can clear a wave quickly or be guaranteed to get all 6 creeps in a wave you should have optimal cs.

my goal is 150 at 20mins every game.

The perfect situation would be 100cs per 10 minutes. Actually attaining 100 per 10 is insane. Getting 80-85% efficiency is ideal. So at 20 minutes 160-170 is the goal. This also hinges on the amount of kills/fights you are in as well. At 20 minutes, if you have 3 kills on top of 170 cs, you're sitting pretty.

Depends on elo?

Well, I guess I'll toss something in for junglers, since no one else really has. Farming for junglers isn't as important as the levels you get for clearing. As a jungler, don't base your success on farm. Keep your level equal to at least the supports, and be ganking if that's happening. If you're behind, go clear for a while to level.