Letter Frequency Table, Including Special Characters?

Does anyone know of a table somewhere for relative frequencies of not just letters, but also punctuation/special characters? I need to use the table to set the letter frequencies for my Huffman code key generation algorithm, but in over half an hour googling I have been unable to find anything that gives a comparison between letters and special characters (I have found letter tables, and I even found one comparing just special characters, but nothing to compare them with each other).