What is the most common middle initial in the USA?

hate to kick up an old thread but I'll dispute the original post of A and S... quite to the contrary...

taking a random sample form census and mixing things up a bit, running with an n=251,869

here's what I found...

9.121% A
3.198% B
4.922% C
9.684% D
8.117% E
2.039% F
2.747% G
2.547% H
0.326% I
6.681% J
2.131% K
15.94% L
6.425% M
1.259% N
1.19% O
1.746% P
0.163% Q
7.536% R
3.825% S
3.598% T
0.066% U
0.86% V
5.572% W
0.024% X
0.198% Y
0.085% Z

So that would make D and L the 2 most common letters... as you'll note A is in contention, but S is far from the top of the list... finally broke down, as this question had been bothering me for quite some time, and wasn't able to find anything concrete. If someone else has done another study of names in this context, contact me... be well.