That was its heyday period - on girls anyway. It seemed like every second or third girl was a
Kelly. I know of and have met far too many to have any set idea about bearers. All types, all sorts - it was that commonly used.
It's an everyday Irish surname, like
Murphy. Both hold the top two spots as the most common surnames in
Ireland I think. I have many surname likes on boys and this is one of them. It's probably futile, but I hope one day it swings completely back.