Hello Mike, welcome - I've seen you on College Confidential...
Go here
http://www.greeklife.ua.edu/docs/Fal...%20revised.pdf
Roughly speaking, 83% pledged, but that doesn't really answer your question. Plus, even if you analyze the figures and come up with an answer, there are some girls who get bids to join, but don't like them and never show up at the house. Or never return for that first new member meeting. Not many, but there are some.
With any luck Zillini will show up here after it's all over and give us some stats.
While you're looking at the spreadsheet, note how many started recruitment in 2001 vs. 2009 - from 708 in 2001 to 1457 in 2009. Wow.