[Air-L] emails and Congress

Hello Air-l, I was hoping one of you might have a statistic for me or a suggestion of where I might go to find it...I am wondering about the number of emails / physical mail Congress receives yearly. I realize this will be a fuzzy number since much of the email is in the form of mass mailings from special interest groups. But if any of you have an idea I'd appreciate it! Thanks so much, Kris