Transform each iteration of an array modifier within defined limits i am currently trying out some rendering for the first time (i was trying to model a pile of paper)

Used a plane, added a solidify modifier (don't judge, i was just messing around with some mods), added a array mod with a relative offset of z=1,2 (i wanted to be able to see the small spaces between each piece of paper, didn't work out though)

Now i wanted to randomly rotate each iteration with max 30 degrees and min -30 degrees so that the pile of paper would look realistic.
So far i tried a limit rotation constraint, simple deform mod and the object offset in the array mod, but none can achieve the result i'm looking for.
Any tips ? 
This is what I got so far. 


The uppermost card was rotated manually and manually editing 100 cards is not an option for me.

and i was planing to use thick paper, so thosehanging down edges are not required for this project (may inform myself about them sometime later on)
found a tut for another program, don't know how to use the mentioned steps in blender
https://www.youtube.com/watch?v=Jm_ENqq-lwI
Make sure each sheet is a separate object. If it's not : in edit mode, press P -> separate by loose parts.
Make sure each object has a decent center
Select all sheets -> Object -> Transform -> Randomize transform


Select delta, an make sure only "rotation" is checked.