Nice.

Cool! Did you find this out yourself (if so, how?) or just use an existing source?

It would be interesting to know the frequency related to uppercase/lowercase…

I found it, but not in a typography-related website.

Where did you find it and how did they determine which two letter combination are most common in English? It's interesting but I would like to know a bit more about how they went about it.

I took it from this website which in turn took it from a a US military manual for Cryptanalysis(they probably use it for decoding messages from terrotists). The information is legitimate, so use it...If you live in the US, you had probably paid for it...

they probably use it for decoding messages from terrotists

They probably use it for decoding messages.

From almost 7 years ago:
http://www.typophile.com/node/5106

hhp

You should really be examining every letter combination as part of your proofing process anyway.

But since design is all about compromise, prioritizing pairs is often relevant.

hhp

Consider that 26 letters can form 676 pairs, (without considering uppercase/lowercase) and if we refer to the study made by Hrant, the letter Q , for example, can be found in only 4 pairs(as opposed by 52), J in 8, Z in 9 and X in 11 etc.