OK, you want statistics? I've got some, courtesy of Poker Academy Pro.
PAP Hand Evaluator will run 100k simulations based on the following variables:
*Hero's Hole Cards
*Known Board Cards (if any)
*Opponents preflop hand selection
Based on these simulations, Hand Evaluator will offer the following:
*% probability that you would win at showdown vs. X number of opponents
*% probability that your opponent(s) will draw to a certain hand (pair, set...etc.)
*% probability that your opponent(s) have made a certain hand
So lets look at a situation with KK and no draws on the flop. Also, we will assume that opponents can only hold top 20% of starting hands:
Hero has

Flop:
PAP HE says:
vs. 1 opponent Hero wins 68%
vs. 2 opponents Hero wins 45%
vs. 3 opponents Hero wins 31%
Even though these numbers are to showdown, in this particular situation we are either way ahead or way behind. So the possible redraws on the turn and river are negligible.
If you consider making a pot sized bet on the flop and we assume Ax and a set will call or raise 100% of the time and everything else folds 100% of the time we can say:
Vs 1 opponent we are ahead about 2/3 of the time, therefore a pot sized bet is EV+.
Vs 2 opponents we are ahead about 45% of the time, so a pot sized bet is EV-. However, a 2/3 or 3/4 sized bet is EV+
Vs 3 opponents we are ahead about 33% of the time, so a 1/3 sized bet is EV neutral (not to mention a pretty ineffective sized bet)
What we are ignoring, however, is the folding equity of our bets. Will AT fold?
We are also ignoring the implied odds of being against someone who will call his JJ or TT down to the river.
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Now, against looser opponents, let's say those who would be in this pot with the top 33% of starting hands:
vs 1 opponents, we win showdown 71% of the time
vs 2 opponents, we win showdown 50% of the time
vs 3 opponents, we win showdown 35% of the time
vs 4 opponents, we win showdown 25% of the time
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Now, against tighter opponents, let's say those who would be in this pot with the top 10% of starting hands:
vs 1 opponents, we win showdown 66% of the time
vs 2 opponents, we win showdown 41% of the time
vs 3 opponents, we win showdown 28% of the time
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I'm sorry about the length of this post. I hope it answers some of the OPs questions and gives a little insight. I also wanted to share a little bit of Poker Academy with y'all.
I will also break this situation down similarly with QQ or JJ if it is requested in this thread.