Here is ChangeLog based stats.  Authors include `tiny change' authors.
Once Org-8.0 is merge the stats for 2013 will show a marked bump.

* Summary 

** Year 2012

Total commits	: 4895
Unique Authors	: 316

| commits | directory               | no. of authors |
|---------+-------------------------+----------------|
|    1454 | lisp/ChangeLog.16       |            151 |
|    1085 | src/ChangeLog.12        |             58 |
|     736 | lisp/org/ChangeLog      |             92 |
|     244 | doc/lispref/ChangeLog   |             24 |
|     230 | lisp/gnus/ChangeLog     |             44 |
|     224 | ChangeLog               |             24 |
|     192 | doc/misc/ChangeLog      |             49 |
|     135 | doc/emacs/ChangeLog     |             16 |
|     108 | nt/ChangeLog            |              9 |
|      84 | lib-src/ChangeLog       |             14 |
|      78 | etc/ChangeLog           |             33 |
|      71 | admin/ChangeLog         |             11 |
|      46 | lisp/url/ChangeLog      |             17 |
|      40 | test/ChangeLog          |             11 |
|      37 | lisp/cedet/ChangeLog    |             19 |
|      34 | lisp/erc/ChangeLog      |             12 |
|      25 | msdos/ChangeLog         |              4 |
|      21 | leim/ChangeLog          |              9 |
|      18 | doc/lispintro/ChangeLog |              5 |
|      11 | lwlib/ChangeLog         |              4 |
|      10 | lisp/mh-e/ChangeLog     |              5 |
|       5 | oldXMenu/ChangeLog      |              3 |
|       4 | nextstep/ChangeLog      |              1 |
|       3 | doc/man/ChangeLog       |              2 |


* Year 2013

Total commits	: 1887
Unique Authors	: 157

| commits | directory                | no. of authors |
|---------+--------------------------+----------------|
|     567 | /lisp/ChangeLog          |             73 |
|     280 | /lisp/ChangeLog.16       |             61 |
|     238 | /src/ChangeLog           |             29 |
|     145 | /src/ChangeLog.12        |             18 |
|     130 | /lisp/gnus/ChangeLog     |             34 |
|      93 | /ChangeLog               |             17 |
|      67 | /doc/misc/ChangeLog      |             23 |
|      59 | /doc/lispref/ChangeLog   |             15 |
|      50 | /etc/ChangeLog           |             23 |
|      47 | /test/ChangeLog          |             16 |
|      36 | /nt/ChangeLog            |              6 |
|      34 | /doc/emacs/ChangeLog     |              8 |
|      33 | /admin/ChangeLog         |              6 |
|      23 | /lisp/org/ChangeLog      |             17 |
|      20 | /lisp/cedet/ChangeLog    |              9 |
|      15 | /lib-src/ChangeLog       |              5 |
|       9 | /leim/ChangeLog          |              4 |
|       9 | /doc/lispintro/ChangeLog |              3 |
|       9 | /lisp/url/ChangeLog      |              3 |
|       9 | /lisp/erc/ChangeLog      |              4 |
|       8 | /lisp/mh-e/ChangeLog     |              6 |
|       2 | /msdos/ChangeLog         |              2 |
|       2 | /nextstep/ChangeLog      |              1 |
|       1 | /doc/man/ChangeLog       |              1 |
|       1 | /lwlib/ChangeLog         |              1 |


Here is the rough recipe.

1. M-x find-name-dired for ChangeLog files
2. % g for ^2012-
3. t k
4. RET all the ChangeLog files
5. M-x multi-occur-in-matching-buffers  on all ChangeLog buffers for  ^2012-
6. In occur buffer, keep only committer name i.e., delete lines nos, email etc
7. delete-duplicate-lines
8. There is also a org-sort-entries and some table magic thrown in.

I had to make some little modification to replace.el, so that it dumps
filenames instead of the buffer names.  I can send in the name of the
authors in each of the above directories that is ChangeLog-ged, if
there is some interest.