Some letters repeat more often than the others

[Suyash1989]

Set of letters {A, E, H, I, M, N, O, S, U} repeat at near about 5-6 times the frequency of other letters such as {B, C, F, G, P, Q, V, W, Y, Z,}. Infact the moment letter Z was first shown, and I entered the code, the learning sequence ended for having reached the count of 26 letters and switched over to the numbers.