what's the most frequently used instant messenger in the us?

when i was still working as a chat support agent in a call center, since our clients are mostly in the U.S. and European countries, they used MSN as their primary IM. here in the Philippines, i think that there are only few people who uses MSN or AIM as IM. here the most popular is Yahoo messenger.

I'm a Malaysian. In my place, most people use MSN. I think almost 80% Malaysian have MSN. Since MSN upgraded their MSN services, I find that it's very useful and very easy to use. Drag and drop pictures, view video, listen to musics, play games, easy access to documents stored in MSN and direct access to my Inbox. So convenient! But this is only my personal view, I have never use AIM before so can't do comparison between these two IM providers.

I know I don't speak for the whole U.S., but I use AIM a lot - and it's really popular in my area, although I do know a few people who use MSN and Yahoo Messenger.