From the list of answers, this is the letter frequency. This might differ slightly from a more general corpus because high-frequency words tend to be short so including 2, 3, and 4-letter words might have a higher proportion of vowels, for example.
e 1233
a 979
r 899
o 754
t 729
l 719
i 671
s 669
n 575
c 477
u 467
y 425
d 393
h 389
p 367
m 316
g 311
b 281
f 230
k 210
w 195
v 153
z 40
x 37
q 29
j 27