These are statistics about the frequency of letters in several languages. They should be taken with some care, since the results depend on the sample that was used, the characters that are assimilated (e.g, is é the same letter as e, ê and è in French?). However, these stats are useful to break cryptographic algorithms.

English
E   12.4%    H    6.5%    U    2.7%    G    2.0%    K    0.7%
T    8.9%    S    6.2%    M    2.5%    Y    2.0%    Q    0.1%
A    8.0%    R    6.1%    W    2.3%    P    1.6%    X    0.1%
O    7.6%    D    4.6%    C    2.2%    B    1.3%    J    0.1%
N    7.0%    L    3.6%    F    2.2%    V    0.8%    Z    0.0%
I    6.7%
French
E   16.7%    T    7.3%    C    3.5%    G    1.1%    J    0.3%
S    8.2%    O    5.8%    P    3.0%    Q    1.1%    Y    0.2%
A    8.0%    U    5.5%    M    2.9%    B    0.7%    Z    0.2%
N    7.9%    L    4.9%    V    1.4%    X    0.6%    K    0.1%
I    7.6%    D    3.9%    F    1.2%    H    0.5%    W    0.0%
R    7.4%
German
E   18.0%    T    5.7%    G    3.2%    F    1.6%    P    0.8%
N   10.6%    D    5.4%    O    2.7%    W    1.5%    J    0.3%
I    8.1%    U    4.6%    C    2.7%    K    1.3%    Y    0.0%
R    7.2%    H    4.1%    M    2.3%    Z    1.1%    X    0.0%
S    6.9%    L    3.3%    B    1.7%    V    0.9%    Q    0.0%
A    6.0%
Italian
E   11.7%    R    7.0%    P    2.8%    F    1.1%    K    0.0%
A   11.7%    L    6.2%    U    2.7%    B    1.1%    J    0.0%
I   11.3%    S    5.1%    M    2.5%    Z    0.9%    Y    0.0%
O    8.7%    C    4.1%    G    2.0%    H    0.9%    W    0.0%
T    7.2%    D    3.9%    V    1.8%    Q    0.4%    X    0.0%
N    7.1%
Japanese

Listing the frequency of all Japanese characters would be rather long and boring, so here are the top 20 most common kanji (chinese characters), along with their (very approximate) meaning. Many thanks to tres equis who provided me with the HTML entities for Unicode characters. You may need Japanese fonts to see them.

日  day, sun     1.43 %       本  book, origin      0.72 %
一  one          1.21 %       長  long              0.60 %
十  ten          1.08 %       中  middle            0.59 %
二  two          0.95 %       五  five              0.55 %
人  human        0.93 %       出  get out           0.54 %
大  big          0.93 %       事  fact              0.50 %
年  year         0.92 %       社  shinto, company   0.49 %
会  meet         0.91 %       市  town              0.49 %
国  country      0.85 %       者  person            0.49 %
三  three        0.74 %       月  month, moon       0.48 %

In Japanese, the 1000 highest-frequency kanji correspond to almost 95% of all use. That percentage is 99% for the 1600 highest-frequency kanji, and 99.9% for the 2400 highest-frequency kanji.

Latin
I   10.1%    S    6.8%    C    3.3%    Q     1.3%   H    0.5%
E    9.2%    R    6.8%    P    3.0%    B     1.2%   J    0.0%
U    7.4%    N    6.0%    L    2.1%    F     0.9%   K    0.0%
T    7.2%    O    4.4%    D    1.7%    V     0.7%   Y    0.0%
A    7.2%    M    3.4%    G    1.4%    X     0.6%   Z    0.0%
Perl

I wish I had statistics about Perl...

Portuguese
E   12.1%    N    6.5%    U    3.3%    F    1.1%    X    0.4%
A   11.9%    T    5.9%    P    3.0%    B    1.0%    J    0.3%
O   11.1%    C    5.1%    L    2.8%    Q    0.8%    W    0.1%
S    7.6%    D    4.2%    V    1.6%    H    0.7%    Y    0.0%
I    7.3%    M    3.8%    G    1.6%    Z    0.5%    K    0.0%
R    7.3%
Spanish
E   13.0%    S    6.9%    U    3.6%    V    1.0%    J    0.3%
A   11.1%    T    5.3%    P    3.0%    F    0.8%    Z    0.3%
O    9.7%    C    5.2%    M    2.9%    Y    0.7%    X    0.2%
I    8.2%    D    4.5%    G    1.4%    H    0.6%    W    0.1%
N    8.0%    L    3.6%    B    1.3%    Q    0.6%    K    0.0%
R    7.7%

Many sources:
http://www.arachnaut.org/archive/freq.html
http://www.fortunecity.com/skyscraper/coding/379/lesson7.htm
http://lists.village.virginia.edu/lists_archive/Humanist/v14/0240.html, cached by Google
http://nozaki-lab.ics.aichi-edu.ac.jp/nozaki/asahi/kanji.html

Log in or registerto write something here or to contact authors.