That's breakage. And no, that amount is not normal. If your hair was shedding, which is normal, there would be a white bulb attached to the hair.

You should do a protein treatment. A hard-core one. I'd suggest Aphogee. Make sure you follow the directions exactly, or you'll end up with more breakage.

Also, how do you detangle? And what kind of comb do you use? You should use a wide-tooth comb, or even better, a Denman brush to detangle. And if possible, try to comb only when your hair is wet, and soaked in conditioner. It'll provide more "slip", making your hair easier to detangle.