How often does your LO bonk their head?

I'm not talking about major falls onto hard floors, but minor bangs. For example, my 9 month old bumps his head on something just about every day. Sometimes that means head butting a coffee table leg, which doesn't even cause him to cry or take notice at all. Sometimes he rolls a little hard and his head hits the very thick carpet ( again though he doesn't even seem to notice). Occasionally he really bonks his head, falling from seated. I of course do my best to prevent falls, and catching 99% of the time, but I still worry about his little brain and wonder if I'm being to casual about it.