I like more the % with kills and not with shots.
I’ll use esea and faceit for example in CS
In esea, hs percentage is counted by how many bullets it takes to hit the head. So most hs percentages are 15-20 percent. If you have 30% means your first bullet accuracy is pretty good.
On faceit and mm it is calculated by how many kills with the headshots you have hit. 20 kills with 10 headshots = 50% hs ratio.