No one that I can think of has ever told me they believe. That may have more to do with the fact that I don’t have religious conversations.
I do remember waiting with great anticipation for the new Planet of the Apes tv show to come on. As soon as it did my grandfather saw the talking apes and went to bed muttering curses under his breath. But he was born in 1885 so allowances must be made.
I think most people I know believe that Creationism exists. 
As for how many hold creationist beliefs themselves, it’s impossible to say, for two reasons.
One, it’s not something I’ve discussed at all with most of the people I know.
And two, the term “creationism” is impossibly vague. Who counts as a creationist? I am always reminded, in threads like these, of the old “Ask the Creationist” thread, in which the OP, after starting the thread with the assertion “Yes, I’m a creationist,” soon followed this up in later posts with “I believe that God created the universe, and that He/She/It guided the development of life. Beyond that I don’t know. I don’t take the Book of Genesis literally” and “I do accept evolution. I just think God gave it a jumpstart.”
Of people I know, less than a third (I know a lot of scientists.)
Of my extended family, definitely more than a third.
I think it’s less than a third.
But I could be blissfully ignorant. It doesn’t come up much.
The vast majority of people I know, most of whom identify as Christians, don’t believe in literal creationism and do believe the theory of Evolution. I’d characterize most of their beliefs as “intelligent design”. They say God created the world but put very little thought into the actual mechanics.
That being said - one day I mentioned to somebody how every atom in their body was created near the core of a long dead star. A nearby girl just looked at me slack jawed and said “you don’t really believe that do you?” before telling me about young Earth creationism. Surprised me, I didn’t know she was that way.
The most religious people I know are my grandparents and I don’t think they believe(d) in it. It surprisingly has never come up.
My aunt and uncle visited the creationist museum last year. Not sure how deeply they believe in it or what their motivation was for visiting. So if anyone, it’s two people I know, that’s it.
I don’t think that’s a fair question. I know plenty of people who believe that “God created the world” but they could never be called Creationists. Most of them don’t spend any time worrying about the fight between the Creationists and the Evolutionist. They aren’t interested in the fine details of how God did it.
Without taking my own poll I suspect about 90% of everyone I know has creationist beliefs in one thing or another, mostly more than one thing.
I have got to meet new people. The subjects I can talk about in front of them is getting too narrow, that is if I want to avoid pointless arguments.
Zero, because I don’t hang out with fucking Creationists.
I voted 2/3, because every Christian I know credits God with creating everything according to His whim. How can anyone claiming to be Christian disbelieve in the creation myth put forth in Genesis?
I don’t know anyone who professes to believe in creationism.
Many years ago, a committed Catholic told me that the official church doctrine was that evolution went on pretty much in a Darwinian way, but that at the instant Homo sap came along, God intervened to insert an immortal soul in him. And somehow in all his get. If this counts as creationist then I guess I know a number of creationists, but I really don’t see it that way. Perhaps the church also thinks that God nudged evolution to go that way; I don’t know.
Some, because I live in a very Mormon/Baptist heavy community and I have to work with these people. But I certainly don’t hang with people with such beliefs, any more than I hang with bigots and Republicans.
I counted family, so it’s way more than a third of people I know. Of my friends, we’re nearing, if not at, zero percent.
A better explanation than mine. All Christians I know use some verbal gymnastics to reconcile what little they accept of scientific “theory” (scare quotes theirs; not mine. I know what a scientific theory entails) with their beliefs that God created everything at his whim. I’ve never encountered a single Christian who believes in evolution as it’s currently understood and also believes in an overseeing supernatural Father.
I belong to a Protestant church that has a significant contingent of young-Earth creationists, but the church overall teaches that there are different arguments about the exact manner in which this happened, how long it took, and how much of the story is meant to be interpreted literally and how much is metaphor and idiom, and that many of these theories are acceptable as long as you believe that God caused the world and humanity to become as it is. How do we know that Adam and Eve did not live in the Garden of Eden for billions of years as immortal beings as the Earth outside the Garden shifted and changed and the universe aged and stars were born and died in the vast reaches of outer space?
I also know several LDS creationists.
Of the devout Catholics I know, I believe they are largely scientific evolutionists if they have any strong theory.
You need to get out more, most Christians believe in evolution and in God - mind you, depending on what you mean by “an overseeing supernatural Father”, then we may not believe in that.
You know of a Christian who believes that God did not create the light, the firmament, the creatures and all that?
Maybe so, because there’s a big difference between what Catholicism teaches and what Catholic individuals believe, but the Catholic schools I went to absolutely would not say a word about evolution.
I’m surrounded by them, it’s the default belief system. This is what I get for being a blue collar worker. 
Depends on how you define creationism. If you consider it to be people who believe it was created in six days in 4004 BC or thereabouts, very few if any, and those who do aren’t going to admit it publicly. If you consider it to be somewhere on the continuum between that and that some higher power created the Earth and Universe, most of them.