There's a lot of contradicting statistics out there, and you have to wonder how they gather the data. I think there's a lot of mis-typing going on too. People mis-type themselves and others a lot.
I thought for a long time I was an INTP, and now the idea seems ridiculous.
Anyway, I can believe that INFJs are rare. I have a hard time believing that ISTJ is the most common, even if very common. I think extroverts out number introverts; I don't buy the almost 50-50 thing. I can say that whatever type is the most common must be the kind I don't click with .
As an INFP, I certainly have gone through life feeling like an alien. It is sooo rare to meet people who "get" me. I realize that INs probably all experience this, just because of our passive & abstract communication styles, and the way it may actually keep us from engaging in conversation with similar people.