[khazhou]

Gender non-conforming is a much wider net. This study you link of 9th and 11th graders, it is not surprising that a large percent (2.7% as you said) reported as trans or GNC.

The original comment above stated "trans", though, not T+GNC.

[pseudalopex]

2.7% identified as transgender, genderqueer, genderfluid, or unsure. The study just used narrow definitions of trans and GNC.