Source: https://linux-hardware.org/?view=os_display_server
Reporting is done by users who voluntarily upload their system specs via
# hw-probe -all -upload
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I would guess not very representative at all. I don't believe wayland usage is higher, like at all. Maybe in a limited setting like NEW installs of the most popular distros, just because they default to it. But the existing install base? No way.
This is a graph of recent reports (one year time frame). The total reports from all time are over 70% X11.
But since the statistics are based on one time uploads, there's no way to know how many of those systems are still in use, or still run X11.