Has research been done (at any level) that gives demographic and other statistical information about the readers of science fiction? I'm curious about age, gender, educational level, reading interests, and so on.
Locus Magazine has an annual poll, dating back into the 1970s. You can search Science Fiction and Fantasy Research Database (http://sffrd.library.tamu.edu) using the subject term "Polls and Surveys" for other sources. The database is not full-text, so you will have to obtain the material from libraries.