That link isn't really credible at all. There are two obvious and major omissions that render their chart meaningless.
They don't say how they determine whether a technology is being used server side -- it could be only if they see ".php" URLs on the site, for example, which would mean there would be a strong bias against languages that make it easy to write sane URLs.
They also don't share what % of sites they're able to make a determination for at all, so these numbers could be based on a statistically insignificant sample.
You only have to go on the job market to see what languages are the most popular; PHP, JAVA and the various .Net (Mostly VB and C#).
JS is on the rise, but no one hires anyone to write just JS. It's usually JS and PHP (and of course, HTML, CSS).
And another point, outside the bubble (I mean a place like Florida) it's hella easier finding a decent PHP guy than Python (or Ruby) guy. I learned that the hard way.
From what I can see, in my area (north England) the job market is almost entirely dominated by PHP and .net openings, with some Java on the side. Ruby and Python only very rarely get a look in, I imagine it would actually be difficult to find work in this area if you only knew Ruby or Python.
The job market in CA is very different to pretty much everywhere else in that emerging and niche technologies tend to be under-represented outside of CA, most likely because of budget constraints in web development, most clients want a simple Joomla or WordPress site and couldn't care less about anything else as long as they don't have to pay over £2,000 for it.
Re: the first para, definitely. I still get emails from recruiters (probably left something up on an old CV site I've since forgotten about), and every single one up north involves PHP and MySQL. The more imaginative roles include a bit of jQuery.
I got the idea from hiring. Look at what was being advertised for; what I was competing against.. But I live in Florida. What area of the country are you?
By default PHP includes an X-Powered-By header in the response containing the PHP version used (should be turned off in production but is often not). This is a more common thing to track.
> which would mean there would be a strong bias against languages that make it easy to write sane URLs
This is false. It is very easy to make sane URLs in PHP. You just designate index.php (or whatever you want, actually) as the default index in your http server. In fact, that's how it works in every language?
They don't say how they determine whether a technology is being used server side -- it could be only if they see ".php" URLs on the site, for example, which would mean there would be a strong bias against languages that make it easy to write sane URLs.
They also don't share what % of sites they're able to make a determination for at all, so these numbers could be based on a statistically insignificant sample.