Letter Frequency Counter (from Larry Israel, http://larry.israel.name/webdev/letterfrequency_plain.html)

Green Eggs and Ham
by Dr. Suess

I am Sam
I am Sam
Sam I am
That Sam-I-am!
That Sam-I-am!
I do not like
That Sam-I-am!
Do you like
green eggs and ham?

L dp Vdp
L dp Vdp
Vdp L dp
Wkdw Vdp-L-dp!
Wkdw Vdp-L-dp!
L gr qrw olnh
wkdw Vdp-L-dp!
Gr brx olnh
juhhq hjjv dqg kdp?