Why does this statistic seem so incorrect?

You know the statistic that says that 10% of people are ? Well, why does it not seem to be that high? In my grade at my school, there are maybe 5 openly gay people, and that is out of a cl of 600 (about). The percentage works out to be 0.833% or about 1%. Where are the other 9%? Are they there, but just not out of the closet, or is it just an erroneous (incorrect) percentage?