This is the standard letter distribution used on Countdown, as supplied by Art Director Demelza Sampson in January 2009, and kindly passed on to me by Charlie Reams. Please note that letters are added and removed from time to time by the producers, so this list does not necessarily reflect the letters used in any particular edition of the programme. For example, an analysis of the first few weeks of Series 63 highlights the fact that the number of G's, V's and W's are all currently increased by 1 and that there may be one fewer N.
A 15
E 21
I 13
O 13
U 5
Total 67
B 2
C 3
D 6
F 2
G 3
H 2
J 1
K 1
L 5
M 4
N 8
P 4
Q 1
R 9
S 9
T 9
V 1
W 1
X 1
Y 1
Z 1
Total 74