I wouldn't make a blanket assumption based on a graph like that. The number of PHP installations are higher for 2 useless reasons:<p>1. It is trivial to see if PHP is installed on a webserver. It is not so trivial to see if Python or Ruby is.<p>2. PHP has a strong presence in shared hosting, which is popular for hobbyist or low traffic websites.<p>When you take into account that big websites like Youtube, Reddit, and FriendFeed are written in Python, these graphs are downright useless.