I just did a quick tally (and anyone feel free to correct me) and this is what I came up with:
(Red) Security personnel: 19
(Red) Support Services: 8
(Blue) Sciences: 3
(Gold) Command: 7
That's the total for the series with the bulk of those happening in the second season. Of those 37 casualties 27 of them are redshirts and 8 of those are Engineering or Support Services. Overall casualties averaged over 3 years = 12.3 deaths per year.
In WNMHGB, Spock reports "Casualties: nine dead," so that should be added to the three you reported. But their shirts are unseen.
Also, along with "Obsession" and "The Changeling", I would add "The Apple" as a major redshirt killer.
"By Any Other Name" has a shocking choice of (red-dressed) victims. Did you tally up how many female crew members Kirk lost overall?
And out of curiosity, how did you interpret the events of "Charlie X"? Did the Thasians save anybody, like the girl turned in to a lizard and the one whose face was wiped out? [Or, better to my liking, her face was briefly covered with a mask that she tore off moments after we leave her.]