This slide shows the median ratio of reference queries to full-time students for all ARL libraries from 1995 through 2003. As you can see, right about 1997 (which would be about the time the Internet started seeing real wide-scale uptake in the U.S.), the number of reference questions we're getting relevant to our student body plummets like a rock. (...) Undergraduates entering universities in the United States use the library as a study space, a socializing space, but to a shocking and frightening extent, they do not use library services or library materials. [...] We're losing clientele; students may come in the library to study, to socialize, to hit the newly installed cafe designed to lure them in, but they're not using library materials, or library services, at anything like the rate they did even ten years ago.

via Peter Bradley, O'Reilly | Association of Research Libraries