They are pretty well split.

Many x86 Chromebooks offer several tiers that obfuscate the data, but in terms of product line releases, they're about 50/50.

Both Samsung Chromebooks, ASUS Chromebook Flip, HP Chromebook 14 G3, Haier and Hisense's both as well, for example, are ARM devices.

Ah, the list of x-86 Chromebooks easily out number the ARM ones available.