Sorry to throw the spanner in the works but I prefer Joomla!
I’ve seen that 18.9% figure floating around for a bit on Twitter now, but I’m interested in the way this was measured. Did they count every site once? Did sites with more traffic (Google, Facebook) get counted accordingly? Did they base this on downloads divided amount of websites? How does anyone even know how many websites there are?
All in all, it’s a nice statistic to generate a buzz, but I’d like to see a bit more context.