I also have not checked the SQL but it looks to me like the Usage column is a simple calculation of (Total Used) / (Total Installed) * 100 to get a percentage.
That calculation would assume that your Total Installed would be higher than Total Used. In your case its not. I'd expect that sort of situation if you'd just set up these software products and software inventory had not run recently (or at all!). Application metering reports usage details in on a daily basis (by default) so its feasible that you'd see usage information exceeding inventory information if inventory has not run.
The content in the Days Metered column suggests you only set application metering very recently for many of these apps. Is that correct?
Is the Inventory Agent installed on all of your end-points? Is an Inventory policy set to run regularly?