how many bytes did each character require for extended ascii characters
Extended ASCII Some multi-byte character encodings (character encodings that can handle more than 256 different characters) are also true extended ASCII. That means all ASCII characters are encoded with a single byte with the value that is used in ASCII to encode that character. They can be used in file formats where only ASCII bytes are used for keywords and file format syntax, while bytes 0x80-0xFF might be used for free text, including most programming languages, where language keywords, variable names, and function names must be in ASCII, but string constants and comments can use non-ASCII characters. This makes it much easier to introduce a multi-byte character set into existing systems that use extended ASCII.
Letter frequency Herbert S. Zim, in his classic introductory cryptography text "Codes and Secret Writing", gives the English letter frequency sequence as "ETAON RISHD LFCMU GYPWB VKJXQ Z", the most common letter pairs as "TH HE AN RE ER IN ON AT ND ST ES EN OF TE ED OR TI HI AS TO", and the most common doubled letters as "LL EE SS OO TT FF RR NN PP CC".[2]