For McLaren it says n=63, but pictured on the graphic is 85 pitstops, of which 22 are painted orange. 22/63 is the figure used for the percentage though.
I think it would help to use to same grid for the squares for all teams. You'd need a grid of 5 by 14, leave the not performed squares black. In that way a higher colored stack means more quick pitstops, a higher stack of grey squares means a higher amount of performed stops overall.