You are more likely to use Wikipedia if you are male (39%), 18-29 (44%), a college graduate (50%), or make more than $75,000 a year (42%). Wikipedia has 24% share of traffic of the top 20 educational web sites. Google Scholar comes in at number 6, Google Book Search at number 7, and the National Library of Medicine (I guess PubMed) at number 9.
I don't think we're doing a good job promoting the electronic library resources available at the state level, like the Ohio Web Library. Anyone in Ohio with a public library card can get instant access to a bunch of EBSCO databases, the Encyclopaedia Britannica, and a lot more.
As easy as that is to say, we all know what the real issue is though. The reason Wikipedia gets so much use is due to the fact that it is dead simple to discover via search. The Pew report points out that Wikipedia articles have a high number of in bound links. Therefore, they display near the top of Google results thanks to the PageRank algorithm.