Americans Remain Woefully Ill-Informed
Wired magazine calls infographics like this "infoporn". I guess you could call this a version of a bubble chart, but it shows a comparison of what people knew in 1989 vs. 2007. Separately it shows knowledge of three questions based on the respondent's usual source of news.
I can't tell how big the sample size was, or what type of people they interviewed. It quotes the source as the Pew Research Center for the People & the Press, but that alone isn't enough to make it credible.