They run 2% of the websites on the internet:
http://www.weebly.com/jobs.php => "Running 2% of all of the websites on the Internet presents some very interesting technical challenges."
http://www.weebly.com/jobs.php => "Running 2% of all of the websites on the Internet presents some very interesting technical challenges."
I don't know for sure if Weebly uses this number to calculate the percentage. But probably not, since it only indicates ~2.8 million Weebly websites, and they claim 11 million (7.8% of that active domain number).
Do they count Facebook/Google, too?