[JeremyNT]

> Compared to previous years or decades (or centuries) there is a markedly higher percentage of children/young adults who "self-identify as 'trans'", often clustered and in waves.

I don't see how you could usefully extrapolate a "real" baseline rate based on what prior generations did. Atypical sexual/gender identities have been taboo for almost the entirety of human civilization, and only as these taboos are now being lifted are people able to express these traits without fear of horrific repercussions.

[the_third_wave]

The current wave of "self-identification" was markedly absent in the wake of the '68 revolts and the ensuing "free love generation" which casts doubt upon your thesis. It is far more likely that these current "self-identification" trends are emergent properties of the availability of direct one-to-many communications media - social media and the like - which make it possible for these identity groups to emerge and grow rapidly.