Really? Huh.
See also the results of this survey https://brashear.me/blog/2015/08/24/results-of-the-2015-slas...
It begins to be old but this section is telling "Which Linux distribution do you primarily use on your server computers?"
Distro #resp %resp prev year
Ubuntu 633 34% 27%
Debian 539 29% 31%
CentOS 214 12% 15%
...
Not a large poll but I didn't find anything better in a quick search on Google.Furthermore the sample is relatively small and my own sample is at least 100x smaller.