My hair is significantly thinner than it was 20 years ago but I have so much of it, that I'm not complaining. The loss is more noticeable when my hair is long as the strands don't just fall out until I'm in the shower (I don't brush or comb my hair during the day) and I end up with a handful of hair. To be perfectly honest, it's the only aspect/sign of aging that I'm actually happy about!

I consider it normal and just a part of aging (unless it suddenly increases or something).