var oLetter = [
['e', 0.13283019823073], 
['a', 0.11962606571693], 
['o', 0.08218623310989], 
['s', 0.06929005640232], 
['n', 0.06734529439310], 
['r', 0.06344311465659], 
['i', 0.05328057305091], 
['l', 0.04894809890022], 
['d', 0.04470843334866], 
['u', 0.04370441304889], 
['t', 0.04354832585943], 
['c', 0.03706859821048], 
['m', 0.03184600522259], 
['p', 0.02294481685067], 
['b', 0.01624150484925], 
['g', 0.01196809071619], 
['h', 0.01162638632845], 
['q', 0.01085438752652], 
['v', 0.00998536155277], 
['í', 0.00930195277730], 
['y', 0.00869025973752], 
['ó', 0.00677080916443], 
['é', 0.00626879901454], 
['f', 0.00601990322594], 
['j', 0.00419747982468], 
['á', 0.00399498833565], 
['z', 0.00325251954254], 
['P', 0.00322298953372], 
['E', 0.00269566794771], 
['x', 0.00236661927803], 
['ñ', 0.00228646639696], 
['A', 0.00221053208857], 
['M', 0.00161149476686], 
['S', 0.00155243474923], 
['D', 0.00144697043202], 
['L', 0.00144697043202], 
['N', 0.00131619467869], 
['ú', 0.00122338607955], 
['C', 0.00115588891654], 
['B', 0.00099980172708], 
['Y', 0.00083527739225], 
['H', 0.00081418452881], 
['Q', 0.00080152881074], 
['T', 0.00077621737461], 
['U', 0.00050622872257], 
['G', 0.00047248014107], 
['V', 0.00045138727763], 
['R', 0.00033326724236], 
['I', 0.00032061152430], 
['O', 0.00030373723354], 
['k', 0.00025733293398], 
['F', 0.00024467721591], 
['J', 0.00008015288107], 
['Z', 0.00006327859032], 
['ê', 0.00004218572688], 
['ü', 0.00004218572688], 
['W', 0.00002953000882], 
['ç', 0.00002953000882], 
['w', 0.00002531143613], 
['Ú', 0.00001687429075], 
['è', 0.00001687429075], 
['à', 0.00001265571806], 
['î', 0.00000843714538], 
['â', 0.00000843714538], 
['ô', 0.00000843714538], 
['É', 0.00000843714538], 
['K', 0.00000421857269], 
['ä', 0.00000421857269], 
['ï', 0.00000421857269], 
  ]

  function getRandomLetter(bRand) {
    if (!bRand) {
      return (Math.floor(Math.random() * 26) + 10).toString(36);
    } else {
      while (true) {

        var nRandom = Math.random();
        for (var z = 0; z < oLetter.length; z++) {
          nRandom -= oLetter[z][1];
          if (nRandom <= 0) {
            return oLetter[z][0];
          }
        }

      }
    }
  }