As crazy as it sounds, there is no Client reporting. Yes, I would love to know who my heavy hitters are.
There's no generic reporting for clients at the time being, many users are wanting this functionality and SolarWinds have picked up on this, they are currently working on this for one of the upcoming releases which will add this functionality to the Technician UI.
At the time being this is not possible to get out of the help desk, you would have to download a ticket list via the Advanced Ticket Search with criteria to filter down to users and tickets, then run your own reports within Excel.
If you got a full ticket list and do this you can get an accurate number to client ratio, although it would probably be better to specify to tickets that have been opened within the last month for more accurate and faster results.
I know you've been on this page before but it's good to have things linked for future reference, as per the Feature Request noted here: Reporting on Clients
Unfortunately I'm at a point where I feel creating/voting on Feature Requests is a waste of time, as evidenced by this situation. Client reporting should be a default feature yet this Feature Request was submitted 4 years ago and we're still waiting.