When a stage hypnotist conducts his show he will need some people on stage that are highly hypnotizeable. To locate those people he will mostly conducts some tests that has the purpose of determining the suggestability of the individuals in the audience. This process has the unfortunate sideeffect that the once who doesn't "succeed" the test, will think that they aren't hypnotizeable, dispite the fact that the setting only allows for the most hypnotizeable people to enter into a trance. To make matters worse a scientist named Ernest Hilgard has applied classic scientific research methods on the subject of hypnosis, where he used a tape recorder and a very monotone voice to hypnotize the subjects. He found that only 10% of the population was hypnotizeable. That is why you might have heard this number before.

The fact is that we all enter the hypnotic state several times each day, and is therefore all "hypnotizeable", if we have a normal working brain. The only reason Ernest Hilgard didn't discover this in his studies is due to the limitations of classical research methods that seeks to have a high degree of reproduceability. To hypnotize someone succesfully a wide variety of techniques and methods can be used, and besides that hypnotizeability has a lot to do with the current state of mind and the desire to be hypnotized. Richard Bandler of NLP has once been challenged to hypnotize a woman who was said to be absolutely not-hypnotizeable. He found that the scientists had succesfully hypnotized her to think that she couldn't be hypnotized, even though that this was not their intention. So he found this woman very hypnotizeable, but the measures with which the scientists were testing the depth of her hypnotic state wasn't suitable in the situation.

Hypnosis is a natural state, and everyone with a normal functioning brain can be hypnotized, if they desire to be hypnotized.