25 is definately not a big pledge class. At Michigan (which has 37,000 undergrads), pledge classes can range from 10-55 girls. It just depends on the house and how successful of a rush they had. My pledge/new member class was 33. I think the average is about 25 and thats with 15 houses (17 when I was there almost 2 years ago). Quota this year is 40.