Just over half of the world's web content is estimated to be in English

"The English domination of the web is completely divorced from the language’s presence in the human population. “Just over half (55.8%) of Web content is estimated to be in English despite the fact that less than 5% of the world’s population speak it as a first language, with only 21% estimated to have some level of understanding,” according to GSMA and Mozilla (pdf). “By contrast, some of the world’s most widely spoken languages, such as Arabic or Hindi, account for a relatively small proportion of the Web’s content (0.8% and less than 0.1% respectively).”"
Source:  Quartz, 6th November 2014