just for the record. some stats.
we take irc logs, only sentences in lojban.
we count the number of words with a given letter multiplied by their frequency divided by the number*frequency of all words. If the same letter occurs more than once in a word we count it as a singular occurrence. We limit ourselves only to the first 3000 most frequent words.
we get:
[x] - found in 2.7% of all spoken in IRC logs words
['] - 16.8%
[c] - 13.9%
[cx'] - 31.75% (at least one of those letters in each word)
[x'] - 19.47% (at least one of those letters in each word)
[cx] followed by a consonant - 2.11%
to'u one of three words contains at least one of the three letters: ['] or [x] or [c].