Statistics of Openings & Transpositions

It seems that while there are literally hundreds of named opening 'systems' which are generally sound, some of which have explored in great detail (eg there are whole books written about Sicilian Opening or Bishops Opening), a different way to consider openings is the frequency of use of particular pieces.  By this, i mean that e4, d5, Nf3, Nf6, Bc4 seem to feature in the majority of openings in different orders or combinations (while something like a3 is something which typcially happens much later on in a game).  I wonder if anyone has systematically explored opening moves from this perspective - I would predict that of all the chess pieces, there are a small majority which are the common denominator to most openings.  I suppose this is consistent with the initial advice you get when starting - develop knights then bishops, dont move a piece twice to begin with, look to get control of d4/d5/e4/e5.... 

Have a look here...

http://www.chess.com/explorer/

There a re similar features built into Fritz and Chessbase (and probably others but these are the ones I know of)

yes, thats interesting - in that e4 and e5 by far dominate all openings.  What this doesnt show is in the case where openings is for example Nf6 whether e4 follows bit later on.  If you were to list which pieces are mobilised within first 10 moves, I reckon top of the list for white would be e4, d4, Nf3, c4, g3, f4, b3 and Nc3 in some order.

You rang?

From the world championship cycle for 2009, top ten moves in the first ten moves for white:

1. Nf3: 471
2. d4: 426
3. Nc3: 341
4. e4: 322
5. O-O: 298
6. c4: 266
7. g3: 120
8. Bg2: 106
9. Be3: 94
10. e3: 86

Top ten moves in the first ten moves for black:

1. Nf6: 448
2. O-O: 303
3. d5: 276
4. Nc6: 246
5. e6: 233
6. c5: 205
7. d6: 189
8. e5: 183
9. Be7: 179
10. a6: 176

that's exactly what I was wondering about.. interesting to see the frequency of castling, particularly for Black.

thank you.  

Visually (missing d6, e3, and e6):