[nonameiguess]

Yes, thank you. The site's methodology disclaimer explains this is the percentage of sites for which they could automatically determine the language in use on the server. Newer web languages don't include a header telling you the language and version in use at all, and if web frameworks add one, security auditors will always make you remove it.

So the real statistic is 78% of websites that are written in a dynamic scripting language, don't get pen-tested, or don't care about security, are written in PHP. That's a very different statistic than 78% of all servers that will respond to an HTTP request.