Surprisingly, whereas there are almost as many Chinese-speaking Internet users as there are English-speaking users, the second core language of the top 10 million websites is actually Russian.

As of March 18th, 2015, the top 10 languages are as follows:

1 English 55.5%
2 Russian 5.9%
3 German 5.8%
4 Japanese 5.0%
5 Spanish 4.6%
6 French 4.0%
7 Chinese 2.8%
8 Portuguese 2.5%
9 Italian 1.9%
10 Polish 1.7%

The source is a pretty serious website, W3Tech, and they are using Alexa to determine the top sites. However, their disclaimer mentions “all the websites whose content language we know”, so maybe it is that Russian websites developers are more diligent at indicating the language in their HTML header?