About 30% of all sites have HTTP/2 support. I don't remember where I saw this. I'm curious why the number is so small because nginx has HTTP/2 out of the box. But if your primary users are using Microsoft IE/Edge I have bad news, this browser has worst HTTP/2 implementation. When we do research on streams prioritization Edge showed that it works like ordinary HTTP/1.1. Safari implementation is based on SPDY, so It has priorities but they never been used in our experiments.