letter frequency 1 .08167 2 .01492 3 .02782 4 .04253 5 .12702 6 .02288 7 .02015 8 .06094 9 .06966 10 .00153 11 .00772 12 .04025 13 .02406 14 .06749 15 .07507 16 .01929 17 .00095 18 .05987 19 .06327 20 .09056 21 .02758 22 .00978 23 .02360 24 .00150 25 .01974