Despite the number of letters increasing, it's still a minority. Additionally, the rate of popularity is slowing.

I am still on the fence whether or not this is a left-handedness situation. (The number of people who are left-handed sharply increased within 1-2 generations once we stopped beating children for primarily using their left hands. But this was generally not considered a social contagion or some grooming behavior from left-handed teachers or something.) If it is, then we should see identification level out within a generation or two.