* No central database: No organization tracks popularity and geekiness in high schools. These are subjective terms.
* Vague definitions: What constitutes "unpopular" and "geeky" varies widely depending on the school, social group, and even individual perception. Someone considered geeky in one school might be mainstream in another. Similarly, popularity is a spectrum, not a binary.
* Self-reporting issues: Even if a survey were conducted, self-reporting on social status and interests is prone to bias and inaccuracy.
While we can't give a number, it's safe to say that there are many students who might identify with these labels in various degrees across all high schools in the world. The perception of being "unpopular" or "geeky" is often more a matter of personal experience and social dynamics than an objective measure.