The Welsh letter frequency (excluding mutations) is as follows:
A - 7.19% B - 1.55% C - 2.41% D - 4.96% E - 5.68% F - 0.99% G - 1.37% H - 0.43% I - 6.93% L - 3.73% M - 2.29% N - 4.97% O - 6.51% P - 1.92% R - 4.69% S - 3.34% T - 3.16% U - 2.44% W - 11.13% Y - 3.34%