I swear Google has published a report from their crawl data about how in/frequently different tags and frameworks were used, in part to determine what they might need to support in Chrome. I'm not able to find this anymore. Does anyone know what I'm talking about?
This is the one that Hixie published back in 2006. It helped guide a lot of the early decision-making in the WHATWG when it came to proposing new tags for HTML5 in a bid to reduce the number of div's out there: