I don't know if anybody is compiling any sort of stats for this, but my results thus far are in line with some of the ratios I'd seen mentioned.
Funny you should ask, I was planning to post what I've gathered over 5 days on multiple characters. Out of 119 abjurations (total number recived, not ilevel 119):
Slot:
45 feet (37.82%)
27 hands (22.69%)
23 legs (19.33%)
18 head (15.13%)
6 body (5.04%)
Level:
52/119 lv75 Abjurations (43.70%)
39/119 lv99 Abjurations (32.77%)
28/119 lv119 Abjurations (23.53%)
*note also that the amount of lv 75/99/119 sets are not equal (8 lv75 sets, 5 lv99, and 11 lv119), so take into consideration that we aren't comparing apples-to-apples in terms of # of pieces within each level.