I guess all rows from that table should be deleted when the user presses “Log out”, as other tables do. At the moment, in version 2.2, none of the rows are deleted, so when you log in with another account, old statistics of input per application remain there.
Actually, none of the tables are emptied out when logging out of the client. I’ve always thought of that as a feature, but with the growing amount of stats, it’s more logical to start fresh from a login, I’ll modify that behaviour in the next version.