Google sampled over one billion documents on the Web to see how HTML is really used, and came up with a number of interesting statistics, including the most popular classes assigned to elements (“footer” is number one) and the average number of different elements used on a Web page (19).

The report is also interesting in that all of the figures are served as SVG files. The SVG stuff looks neat but the figures render incredibly slowly in Firefox 1.5 on my Powerbook.