In what way are they citizen soldiers? The statistics I can find suggest that active duty personnel majorly out reserve personnel.

Active duty personnel cannot be considered citizen soldiers because their service is not compulsory and they are full-time professionals, not merely civilians in service.

Reservists might be considered citizen soldiers, if you're a bit loose with the criteria that service must be a compulsory civic duty.

Army Active Duty 472,047

Army National Guard 345,153

Army Reserve 219,054

I believe a significant number of soldiers also only do 4 or 8 years and then return to civilian life, they aren’t a permanent military class like the Roman legions or whatever. As you mention a lot depends on what you consider a “citizen soldier” though.