I think it depends on where you live...here in the SC/GA area many people have 3 or 4 and several at our church have 4+ kiddos. I would say on average though 4 or more is "many". We have number 4 on the way and we've started to get those responses from some around here but mostly family that don't live around here.
Wife to K
homeschooling mom to A(2-24-02)
and our newest addition A(3-11-11)