I got that from the majority of the girls playing anything from lower D1 through D3. Granted a lot of the "bigger" girls playing high to mid-level D1 will be swinging a 33 or 34 inch bat. However, there are many more smaller girls that won't or can't compete at that level that are swinging the smaller bats. 33 is by far the most popular but 32 still comes in second especially at the lower levels where you find girls of small stature playing.
ETA: Think about how many D1 colleges there are versus D2 and D3 combined.
Yocoach - but, and with all due respect, how did you get that "from the majority of girls playing anything...."? This has been a question we've grappled with for a couole years now and there does dont seem to be any true consensus out there. I completely agree with your earlier comment about swinging a bat that won't compromise your mechanics. Great discussion here!