Starfleet tends to be very officer heavy, about 40% I think. But ground forces will probably be different. In Prime Directive, a Prime Team (basicly an RRT) had about 6 members, of course the mandatory positions/character stereotypes are; the veteran officer (cmmdr or major), tough senior NCO(Sgt. Maj. or Master Chief), a medic, and heavy weapons, a couple of junior officers and a couple of junior NCOs. Usually no ensigns or privates. In regular ground forces you'd probably see more privates and ens./2LTs.
"Retreat?! Hell, we just got here!", annonymous American Marine, WWI
"Gravity is a harsh mistress....", The Tick