Hah! It's actually my 23rd birthday today. I've talked to a quite a few people about this and most seem to think we've been going downhill since at least the early 1990's. Some would point back as far as the 60's.
I picked 1999 since I don't think I've ever talked to someone who chose a later date than that.
Of course, people from 2nd world and 3rd world countries likely have different views.