why do pledge classes get smaller as the years go by?

[pinkprtygirl]

sorry im new here and dont really know where this question belongs. i'm thinking of rushing a sorority here in the next month when i start school (but my question isn't about recruitment) and was curious about something i noticed.

i have a couple friends who are in different sororities and they always posts pictures of their pledge class every year they go back to school for recruitment. they're both seniors this year and when i've looked at all their pictures since freshman year i noticed that both of their pledge classes are considerably smaller. freshman year it looked like about 40 girls, sophomore year seemed about 25-30, junior year 15 or so, and this year her pledge class seems to have shrunk to about 8-10.

is this normal??? what happend to those other 30 girls who were so excited to be your 'sister' when they joined? you expect people to drop out and stuff but i've read all this stuff about how sorority girls graduate at a higher rate and stay in college longer because they had that support system but then why do pledge classes get smaller? like do that many girls really get kicked out or just drop out because they don't like it? sorry if this is a dumb question i really don't know too much about sorority stuff yet i'm trying to learn. thanks!