Wow.  So of the 256 values a byte can have:
* 6 are encoded as two characters (the ones in the table above)
* N (the ascii control characters) are encoded as 6 characters
* 256 - (6 +N) are encoded as a single character

Should we list off the ASCII control characters?  http://en.wikipedia.org/wiki/Control_character lists 33 and your table above has 3 (LF FF CR), so N = 30??