HTTP/2 usage statistics in June 2015
The percentage of visitors using HTTP/2 on this site was higher than I initially expected. Granted the audience was likely to be more technologically aware than the average reader of an excellent celebrity gossip site.
I will argue that even if this week long sample does not represent the general public, it is definitely not irrelevant. Thanks to evergreen browsers it has never been as likely for web developers to be using the same browsers as the consumers of that content. Quite unlike installing Mozilla Phoenix back in the day.
There is quite a bit of HTTP/1.1 traffic from social media robots, etc, which do not download all the resources. But as the bulk of traffic was done with it - it's safe to say HTTP/2 is most definitely here today.
It is also worth noting that out of 1463 individual browsing sessions, only 9 were done with Microsoft Internet Explorer. This is probably not very indicative of the general public, but more of a tendency for web developers' preferences.
As Microsoft rolls out Windows 10 in the immediate future it'll increase the number of potential clients as Microsoft Edge browser supports HTTP/2 out of the box.