TechCrunch interview with Toni Schneider, the CEO of WordPress.com’s parent company Automattic.
“Overall, if you look at the entire Internet and just go down the list at what all the different sites run… 17.4 percent of all sites on the Internet are powered by WordPress. The next number two platform is Joomla, which is around 3 percent, and Drupal is around 2 something. And then, I believe Blogger is number four with one or 1.5 percent.
If you notice, that doesn’t add up to 100 percent. So actually, the majority of the web is still custom made sites that don’t even use a content management system.”
WordPress.org is the open source version to download and run yourself, and WordPress.com is run as a service.