Less than half of them.
I have a new idea to personality types.
One famous actor commented on another actor's style of keeping the act up even when the camera wasn't on. He said: "he must be a bad actor".
This is something I can subscribe to. An able person can change appearances like someone can change their cloths, and it is not a mark of insanity. On contrary, it is insanity to belive that one's face (or clothes) is a permanent (and immutable) factor of one's life.
I do recognize that keeping the same persona over many years is beneficial to one's career, mostly because of the idiots who have trouble figuring out a person's standpoint unless it keeps the same for 20 years.
In essence, the habit of staying the same is adjustment to the fact of most people being idiots. And lazy.
Well, that was some talk, wasn't it?
Edit: if you want some self-criticism to what I just said, I'll happily provide it just here. It might be that I'm just a crazy person and I'm opposing stability because I'm unable to display stability myself, in which case you would do best to just disregard all what I just said.
On the other hand, if someone is able to think of many stances to life, and act the part in every situation, he will become an 1, an 7, a 6 or a 4 for that part - and stay quite sane for the whole experience.