How Much Shedding Is Normal?

[dfspcc20]

I've grown my hair out much longer than I ever have in my life (~1.5 years w/o a haircut now). How much hair is "normal" to see when combing, in the shower drain, etc.? With short hair I would never notice shedding, but with longer hair, its more obvious. No signs of receding hairline or male-pattern baldness.