Ə - 13.23% E - 12.60% A - 7.47% N - 7.11% R - 6.94% T - 6.91% O - 6.83% I - 6.71% S - 4.75% D - 4.21% L - 3.96% K - 3.18% Ð - 2.95% M - 2.76% Z - 2.76% P - 2.15% Æ - 2.10% V - 2.01% W - 1.95% U - 1.93% B - 1.80% F - 1.71% H - 1.40% Ŋ - 0.99% C - 0.97% J - 0.81% G - 0.80% Ȝ - 0.59% Q - 0.56% Y - 0.50% Þ - 0.41% Ñ - 0.17% Ƿ - Probably 0.15% Œ - 0.10% X - 0.07%
Source: https://cmloegcmluin.wordpress.com/2012/11/10/relative-frequencies-of-english-phonemes/ For Ñ, I just used how frequent it is in Spanish, and for Ə, I added the frequencies of the /ə/ and /ʌ/ sounds. Credit 2 Every1.
