From: Northwestern Georgia, USA
Two-thirds of the general population is extroverted. One-third is introverted.
Pardon me for stating the obvious, but being introverted does not mean one is shy. Introverts enjoy company, deep friendships, meaningful conversation, teaching, public speaking and a host of other activities. But introverts are drained by social interaction and need down time to recharge batteries. Down time in the form of reading, music, art, etc. Extroverts, on the other hand, are energized by social interaction. They do not require down time since their batters are constantly recharging in social engagements.
Two-thirds of Appalachian Trail backpackers are introverts, flipping the percentage found in the general population.
I'd guess more than half of gamers are introverts, but there are many, many exceptions in these forms. In the AE forum that I'm most familiar with, Geofflamber and John III are obvious extroverts. Bullwinkle58 and myself are introverts.
Fun stuff to study and think about.