I will share some of my experience in an attempt to answer you question/s, Student of Trinity.
I believe, most of the regular Orgs (vs. poster or Advanced Orgs) have anywhere between 25 and 50 staff members (sometimes much less, sometimes a little more).
Per my observations, there are normally only 3 to 5 people in an Org who work directly on advertisements, but they work long, hard hours for sure. It's being done in a direct coordination with an Org top Execs and in case of a major event/evolution - all the way to top management (through telexes, emails and otherwise).
Then, there is Public Division. Those folks normally work their asses off really hard to get new people in through book sales, testing, films, surveys, what have you. Also, keeping the current people on their courses/Book One auditing, making sure they resign to major services (Bridge auditing/training) and trying to recover "blown" ones. That's a front line and can be a real bitch, even though sometimes rewarding (when people get benefits/real wins).
Now, the auditing part. Most of the regular Orgs probably have anywhere between 4 and 10 reliable, classed Auditors who constantly deliver the bridge actions (which is the main source of the income, despite of the LRH's HCO PL "Booming Orgs Through Training". Most of them are really cool, motivated and well-intentioned people, per my experience. They believe in tech and they really want and try to help another (when they are not in cramming or ethics.)
There also Registrars (Income people). Two categories I know of. The best ones I know were the worst people I ever met. I am not sure if they are even human, capable of love or simply affinity. Second ones (juniors of the first ones), were very conflicted, mostly good people.
And then there are the rest of good folks, like Treasury guys (least bothered), Course Supervisors (it's always their fault, if things go wrong), Qual (see Course Supervisors above), HCO (just lame), etc.
Basically, it's a bunch of people with good intentions, who most likely were misleaded, to begin with, trying to make things go right.
Not sure if I answer the percentage question, but I hope it gives you some idea.
Wish you well.